Bletchley Park

Bletchley Park

With the emergence of Adolf Hitler in Nazi Germany the British government began planning for the possibility of war. MI6 began purchasing sites that might be needed for its wartime needs. In 1937, the owner of Bletchley Park, an estate that included a large Victorian country house, died. Built by the financier, Herbert Leon, in 1883, it was situated 50 miles north-west of London. "Its red-brick facade boasted neither symmetry nor beauty: it was an electric assemblage of gables, crenellations, chimney-stacks and bay windows... Tucked behind it were the usual outbuildings: stables, garages, laundry and dairy facilities, and servants' living quarters." (1)

Sir Hugh Sinclair, the head of MI6 purchased Bletchley Park for £7,500. It was the tenth site acquired by the organization and was given the name "Station X". It was decided to make it the base for the Government Code and Cypher School (GCCS). The head of GCCS, Alastair Denniston, realised that in order to deal effectively with the increasing amount of secretly coded messages he had to recruit a number of academics to help with their work. One of Denniston's colleagues, Josh Cooper, told Michael Smith, the author of Station X: The Codebreakers of Bletchley Park (1998): "He (Denniston) dined at several high tables in Oxford and Cambridge and came home with promises from a number of dons to attend a territorial training course. It would be hard to exaggerate the importance of this course for the future development of GCCS. Not only had Denniston brought in scholars of the humanities of the type of many of his own permanent staff, but he had also invited mathematicians of a somewhat different type who were especially attracted by the Enigma problem." (2)

Bletchley Park was selected as it was more or less equidistant from Oxford University and Cambridge University and the Foreign Office believed that university staff made the best cryptographers. Lodgings had to be found for the cryptographers in the town. Some of the key figures in the organization, including its leader, Alfred Dilwyn Knox, always slept in the office. (3) Hugh Alexander and Stuart Milner-Barry were installed at the Shoulder of Mutton Inn, in Bletchley. Milner-Barry later recalled: "Hugh and I were most comfortably looked after by an amiable landlady, Mrs Bowden. As an innkeeper, she did not seem to be unduly burdened by rationing, and we were able (among other privileges) to invite selected colleagues to supper on Sunday nights, which was a great boon." (4)

Frank Birch and Gordon Welchman were billeted in the Duncombe Arms at Great Brickhill. Another member of staff, Barbara Abernethy, later recalled that Birch was a popular figure at Bletchley Park: "He (Birch) was a great person. I knitted him a blue balaclava helmet which he wore throughout the war. He was billeted in the Duncombe Arms at Great Brickhill. They had a lot of dons there, Gordon Welchman, Patrick Wilkinson. It was full of dons all the time. All of them having such a jolly time that they called it the Drunken Arns." (5)

The top floor of the house was taken by MI6. The main body of GCCS, including its Naval, Military and Air Sections were on the ground floor. This included the office of Alastair Denniston that "looked out across a wide lawn to a pond, with attractively landscaped banks". (6) At first, the codebreakers, under the control of Alfred Dilwyn Knox, were allocated working space in "a row of chunky converted interlinked houses - just across the courtyard from the main house, near the stables". It became known as the "Cottage". (7) Knox's department consisted of ten people, including "two very brilliant" young women, Margaret Rock and Mavis Batey. (8) Mavis later recalled. "We were all thrown in the deep end. No one knew how the blessed thing worked. When I first arrived, I was told, 'We are breaking machines, have you got a pencil? And that was it. You got no explanation. I never saw an Enigma machine. Dilly Knox was able to reduce it - I won't say to a game, but a sort of linguistic puzzle. It was rather like driving a car while having no idea what goes on under the bonnet." (9) "We were looking at new traffic all the time or where the wheels or the wiring had been changed, or at other new techniques. So you had to work it all out yourself from scratch.” (10)

Inside the grounds of Bletchley Park they built several prefabricated wooden huts. In the intitial stages of the war the huts served different purposes: Hut 1 (Wireless Station and from March 1940, the home of the first Bombe, "Victory"); Hut 2 (recreational area that provided tea and beer); Hut 3 (translation and analysis of Army and Air Force decrypts); Hut 4 (Naval Intelligence); Hut 5 (military intelligence including Italian, Spanish, and Portuguese ciphers and German police codes) Hut 6 (cryptanalysis of Army and Air Force Enigma); Hut 7 (cryptanalysis of Japanese naval codes and intelligence) and Hut 8 (cryptanalysis of Naval Enigma). Later other huts were built to house decryption machines. These huts were like small factories. In September 1943, when Stuart Milner-Barry was promoted head of Hut 6, it comprised about 450 staff.

Francis Harry Hinsley was originally sent to Hut 3: "Hut 3 was set up like a miniature factory. At its centre was the Watch Room - in the middle a circular or horseshoe-shaped table, to one side a rectangular table. On the outer rim of the circular table sat the Watch, some half-dozen people. The man in charge, the head of the Watch or Number 1, sat in an obvious directing position at the top of the table. The watchkeepers were a mixture of civilians and serving officers, Army and RAF. At the rectangular table sat serving officers, Army and RAF, one or two of each. These were the Advisers. Behind the head of the Watch was a door communicating with a small room where the Duty Officer sat. Elsewhere in the Hut were one large room housing the Index and a number of small rooms for the various supporting parties, the back rooms. The processes to which the decrypts were submitted were, consecutively, emendation, translation, evaluation, commenting, and signal drafting. The first two were the responsibility of the Watch, the remainder of the appropriate Adviser." (11)

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Oliver Lawn worked in Hut 6: "I was concerned with the codebreaking and that was it. When the code had been broken, the decoded message was passed through to the Intelligence people who used the information - or decided whether to use it. The content of messages was of no concern to me at all. I knew enough German to get an idea of what it was all about. But I had no idea of the context. And it wasn't my business. I could read the messages but they were so much in telegraphese, jargon, that they would mean nothing." (12)

Peter Twinn pointed out that it was very much a team effort: "When the codebreakers had broken the code they wouldn't sit down themselves and painstakingly decode 500 messages. I've never myself personally decoded a message from start to finish. By the time you've done the first twenty letters and it was obviously speaking perfectly sensible German, for people like me that was the end of our interest." The message was now passed on people such as Diana Russell Clarke: "The cryptographers would work out the actual settings for the machines for the day. We had these Type-X machines, like typewriters but much bigger. They had three wheels, I think on the left-hand side, all of which had different positions on them. When they got the setting, we were to set them up on our machines. We would have a piece of paper in front of us with what had come over the wireless. We would type it into the machine and hopefully what we typed would come out in German." (13)

Phoebe Senyard brought in a top chef from London to look after the codebreakers and the meals, laid out on longtables in one of the downstairs rooms of the house and with full waitress service. Phoebe Senyard later recalled: "What I remember very well were the wonderful lunches with which we were served. Bowls of fruit, sherry trifles, jellies and cream were on the tables and we had chicken, ham and wonderful beefsteak puddings, etc. We certainly could not grumble about our food." (14)

Most of the other women working at Bletchley Park agreed with Senyard. Jean Valentine commented: "The food was great at Bletchley Park.... I think there was a vegetable garden just over the stone wall." Shelia Lawn recalls "One day, I went to see a film, and then, I was hungry, so I went into what was called the British Restaurant. And I thought: This isn't half as good as our canteen. I thought it was a terribly dull meal." (15)

Sarah Baring, the daughter of the Richard Henry Brinsley Norton, 6th Lord Grantley, was used to having meals of a high standard. She was less impressed with the food at Bletchley Park and describes one scene involving her friend Osla Benning : "We thought a lot about food. Night watches were especially vulnerable to rumbling tummies and usually forced us to go down to the canteen at 3 a.m., where the food was indescribably awful. It is a well-known fact that to cater for so many people is difficult, and particularly in wartime ... but our canteen outshone any sleazy restaurant in producing sludge and the smell of watery cabbage and stale fat regularly afflicted the nostrils to the point of nausea. One night I found a cooked cockroach nestling in my meat, if you can dignify it by that name, the meat not the beetle. I was about to return it to the catering manageress when my friend Osla, who had the appetite of a lioness with cubs, snatched the plate and said: 'What a waste - I'll eat it!' How she managed to eat so much - minus the insect - and stay so slim I never knew, because any leftovers on any nearby plate were gobbled up by her in a flash." (16)

There was a lot of romance at Bletchley Park. Keith Batey became involved with Mavis Lever. He felt guilty about working at the Government Code and Cypher School while so many of his contemporaries were risking their lives in open combat. "Accordingly he told his bosses that he wanted to train as a pilot, only to be informed that no one who knew that the British were breaking Enigma could be allowed to fly in the RAF, the risk being that he might be shot down and captured. Batey then suggested that he join the Fleet Air Arm, flying over the sea in defence of British ships, arguing that he would be either killed or picked up by his own side. Worn down by his persistence, his superiors reluctantly agreed." Keith married Mavis in November, 1942, shortly before he left for Canada for the Fleet Air Arm advanced flying course. (17)

Oliver Lawn fell in love with Shelia MacKenzie, another codebreaker at GCCS. Oliver later recalled that several other codebreakers married while working at Bletchley Park, including Robert Roseveare and Dennis Babbage: "There was quite a bit of romance. There were several in Hut 6 who married while they were at Bletchley. There were the Bateys, of course... The other couple I recollect was Bob Roseveare and Ione Jay. He was a mathematician, straight from school. He hadn't even gone to university. Very brilliant chap from Marlborough. He married Ione Jay, who was one of the girls in Hut 6. Then there was Dennis Babbage, who was a don similar to Gordon Welchman. Same sort of age. Babbage married while he was there." (18) Shelia and Oliver married in May 1948. (19)

In the planning for the wartime Bletchley Park, Denniston's principal helpers, in Robin's recollection, were Josh Cooper, Nigel de Grey, John Tiltman, Admiral Sinclair's sister, and Sir Stuart Menzies. Edward Travis, whose later performance as successor to Alastair Denniston at Bletchley Park was so significant, must have been involved, but he was not one of the "family" team that dated back so many years. Robin believes that, before joining GCCS, Travis was involved in encipherment rather than codebreaking.

As preparatory work was being done, Denniston visited the site frequently, and made plans for construction of the numerous huts that would be needed in the anticipated wartime expansion of GCCS activities. When war actually came, these wooden huts were constructed with amazing speed by a local building contractor, Captain Hubert Faulkner, who was also a keen horseman and would often appear on site in riding clothes.

The word "hut" has many meanings, so I had better explain that the Bletchley huts were single-story wooden structures of various shapes and sizes. Hut 6 was about 30 feet wide and 60 feet long. The inside walls and partitions were of plaster board. From a door at one end a central passage, with three small rooms on either side, led to two large rooms at the far end. There were no toilets; staff had to go to another building. The furniture consisted mostly of wooden trestle tables and wooden folding chairs, and the partitions were moved around in response to changing needs.

The final move of the GCCS organization to Bletchley was made in August 1939, only a few weeks before war was declared. As security cover the expedition, involving perhaps fifty people, was officially termed "Captain Ridley's Hunting Party," Captain Ridley being the man in charge of general administration. The name of the organization was changed from GCCS to "Government Communications Headquarters" or GCHQ.

The perimeter of the Bletchley Park grounds was wired, and guarded by the RAF regiment, whose NCOs warned the men that if they didn't look lively they would be sent "inside the Park," suggesting that it was now a kind of lunatic asylum.

Denniston was to remain in command until around June 1940, when hospitalization for a stone in his bladder forced him to undertake less exacting duties. After his recovery he returned to Bletchley for a time before moving to London in 1941 to work on diplomatic traffic. Travis, who had been head of the Naval Section of GCCS and second in command to Denniston, took his place and ran Bletchley Park for the rest of the war. In recognition of his achievements he became Sir Edward Travis in 1942.

In spite of his hospitalization, Denniston, on his own initiative, flew to America in 1941, made contact with leaders of the cryptological organizations, and laid the foundations for later cooperation. He established a close personal relationship with the great American cryptologist William Friedman, who visited him in England later. The air flights were dangerous. On Denniston's return journey a plane just ahead of his and one just behind were both shot down.

Oliver and Sheila Lawn both worked at Bletchley Park in Buckinghamshire, the very secret wartime code breaking establishment. It was called the Government Communications Headquarters (GCHQ). All the work done at Bletchley Park remained Top Secret for some 30 years after the war, and only then were Oliver and Sheila able to talk about their work there.

Oliver Lawn was recruited for Bletchley Park by Gordon Welchman in July 1940. He had just completed a Mathematics Degree at Jesus College, Cambridge, and had expected then to be called up into the Army, as many of his contemporaries were being. Gordon Welchman, a Cambridge Mathematics Don, had been recruited for Bletchley at the beginning of the War in September 1939, along with other Oxford and Cambridge Dons, who included Alan Turing. In July 1940 Welchman was recruiting other Mathematicians, and Oliver was one of these.

He joined a team with Welchman in Hut 6 at Bletchley Park, which was concerned with breaking the Enigma Codes used by the German Army and Air Force. (The Enigma Codes used by the German Navy were different, and were broken by a quite different group of people, in Hut 5.) He remained in Hut 6 for 5 years, until September 1945.

The methods mostly used for breaking these Enigma Codes were by guessing "cribs" - that is, guessing what some part of an encoded message actually said, in German. This was of course only possible for "routine" messages such as daily weather reports or forecasts, which often began, or ended with a standard phrase, or a record of the time of sending (e.g. "Wettervorhersage" or "nullsechsnullnull" "0600" hours). By aligning such phrases with the encoded text which was received over the radio in Morse code, pairs of text letters and encoded letters were thrown up, and these were grouped into "menus" looking rather like diagrams of Euclidean Geometry. The menus were then tested by large machines called "Bombes", seeking the correct setting of the Enigma machine at which the message had been encoded - the daily "key". When this "key" had been found, all the messages on that key, and on that day, could be decoded. Keys changed daily at midnight, and each day's key had to be separately discovered. There were separate daily keys for different parts of the German Services. The total number of possible Keys was 150 million million million.

Dilly himself always slept in the office, going back to Courn's Wood once a week. His driving was worse than ever. His mind was totally elsewhere. Fortunately he drove slowly. "It's amazing how people smile, and apologise to you, when you knock them over," he remarked.

In time the buildings inside the Park walls extended into blocks of huts and cafeterias, and by the end of the war the personnel numbered more than seven thousand, increased by observers and liaison men and important visitors in uniform. With all this Dilly had nothing to do. At first his department consisted of ten people, though these included, besides Peter Twinn, two very brilliant and sympathetic young women, Margaret Rock and Mavis Lever (now Mrs Batey). They were accommodated in a small cottage overlooking the old stable yard.

He would, however, need more ciphering clerks-not the vast numbers which eventually made the Treasury complain that "Bletchley was using up all the girls in the country," but still, a section of his own. Into this task Dilly entered with quite unexpected enthusiasm, and when the assistants arrived down from London with the files they were surprised to find him surrounded with pretty girls, all of them, for some reason, very tall, whom he had recruited for the work. The girls took from four to six months to train, though this was not undertaken by Dilly, who never trained anybody, but by a capable and understanding woman, Mrs Helen Morris. They worked on the equations in three eight-hour shifts, and when Dilly wanted to speak to them or to the punch-card operators who registered the encipherments as dots, he would limp across from the cottage, often in his grey dressing gown, indifferent to rain and snow, to tell them his new idea.

We thought a lot about food. but our canteen outshone any sleazy restaurant in producing sludge and the smell of watery cabbage and stale fat regularly afflicted the nostrils to the point of nausea.

One night I found a cooked cockroach nestling in my meat, if you can dignify it by that name, the meat not the beetle. I was about to return it to the catering manageress when my friend Osla, who had the appetite of a lioness with cubs, snatched the plate and said: `What a waste - I'll eat it!' How she managed to eat so much - minus the insect - and stay so slim I never knew, because any leftovers on any nearby plate were gobbled up by her in a flash.

Alan Turing - School Student (Answer Commentary)

(1) Michael Paterson, Voices of the Codebreakers (2007) page 46

(2) Michael Smith, Station X: The Codebreakers of Bletchley Park (1998) page 16

(3) Penelope Fitzgerald, The Knox Brothers (2002) page 228-229

(4) Sinclair McKay, The Secret Life of Bletchley Park (2010) page 61

(5) Barbara Abernethy, quoted by Michael Smith, the author of Station X: The Codebreakers of Bletchley Park (1998) page 26

(6) Gordon Welchman, The Hut Six (1982) page 31

(7) Sinclair McKay, The Secret Life of Bletchley Park (2010) page 13

(8) Penelope Fitzgerald, The Knox Brothers (2002) page 229

(9) Mavis Batey, interviewed by Sinclair McKay, for his book, The Secret Life of Bletchley Park (2010) page 51

(10) The Daily Telegraph (13th November, 2013)

(11) Francis Harry Hinsley, quoted by Michael Paterson, the author of Voices of the Codebreakers (2007) page 55

(12) Oliver Lawn, interviewed by Sinclair McKay, for the book, The Secret Life of Bletchley Park (2010) page 189

(13) Diana Russell Clarke, quoted by Michael Smith, the author of Station X: The Codebreakers of Bletchley Park (1998) page 34

(14) Phoebe Senyard, quoted by Michael Smith, the author of Station X: The Codebreakers of Bletchley Park (1998) page 5

(15) Sinclair McKay, The Secret Life of Bletchley Park (2010) page 143

(16) Sarah Baring, The Road to Station X (2000)

(17) The Daily Telegraph (2nd September, 2010)

(18) Oliver Lawn, interviewed by Sinclair McKay, for the book, The Secret Life of Bletchley Park (2010) page 196-197

(19) Roger Marsh, Shelia and Oliver Lawn (31st August 2005)

The Enigma Machine Declassified: Beyond Bletchley Park

Since some of the documents are, to this day, yet to be declassified, the complete story of how the German&rsquos Enigma code was broken during World War II may never be completely known. The popular version, as portrayed in The Imitation Game , is that British mathematicians, chess players, and puzzle masters at Bletchley Park in England, led by the brilliant Alan Turing , worked out a method to decrypt the German military&rsquos message traffic. The truth is far more complex and involves a cast of &ldquohidden figures&rdquo who never received full recognition for their amazing contributions.

Even a cursory examination of the history surrounding the British code-breaking operation at Bletchley Park hints at evidence that contradicts &ndash or at least complements &ndash the popular version of how the German Enigma code was broken. After intelligence services, in the 1990s, finally declassified many of the documents related to Bletchley, a fuller story has been long known and reported on. More recently, Sir Dermot Turing, Alan&rsquos nephew, wrote a book to correct the record and reveal a cast of cryptologists, spies, and others who have more claim to breaking Enigma than the lone-genius Turing.

The less well-known version of events involves Polish mathematicians and a French spy master. The Poles were hidden figures much like the women in the popular movie of the same name. Their amazing cleverness allowed them to decrypt Enigma-encoded messages years before the British at Bletchley. But the accepted story of who cracked the Enigma code gained prominence because Eastern European mathematicians didn&rsquot fit a mythical image of Oxbridge-educated linguists defeating the Nazis.

In France, a savvy espionage chief formed a crucial link between the Poles and the British. He has remained hidden from view, perhaps because he knew too much of a far messier backstory about Enigma than had been represented in popular history.

And all the principals of this shadowy story, Turing included, were subservient to the strange logic of state secrecy that forced everyone to conceal their work and accomplishments long after the war was over and their enemies defeated.

Even the Enigma machine itself is something of a hidden figure, and its origins are far more benign than one might first suspect. It&rsquos actually a good place to begin to untangle a truer story of how Alan Turing and his team eventually achieved their well-publicized successes.

Your guide to Alan Turing: the man, the enigma

We bring you the facts about the life and death of Alan Turing, who played a vital role in breaking German codes including Enigma during the Second World War and is considered by some to be the founding father of computing.

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Published: May 26, 2021 at 2:00 pm

How much do you know about Alan Turing, who was portrayed by Benedict Cumberbatch in the 2014 film The Imitation Game? Discover more about his life, death and legacy with our essential guide…

The life of Alan Turing: a timeline

23 June 1912 Born Alan Mathison Turing in Maida Vale, London, the second son of Julius and Sara Turing

October 1931 Turing takes up a mathematics scholarship at King’s College Cambridge, earning a first-class degree. In 1935 he is elected to a junior research fellowship

January 1937 A paper by Turing is published that is later recognised as laying the foundation of computer science

June 1938 At the age of 25, Turing receives his PhD from Princeton for his dissertation Systems of Logic Based on Ordinals

4 September 1939 Turing arrives at Bletchley Park to begin his wartime work on code and cipher systems. He goes on to lead the team in Hut 8 (left)

March 1940 The first Bombe machine, designed by Turing, arrives at Bletchley. More than 200 machines will be manufactured

2 November 1942 Turing travels to the US to liaise on several joint US/UK projects, including an American Bombe machine

March 1946 Turing produces a detailed design for an Automatic Computing Engine

31 March 1952 He is convicted of being “party to the commission of an act of gross indecency”

8 June 1954 Turing is found dead. The coroner’s verdict is that he had taken his own life

Alan Turing: his life, achievements and legacy

The founding father of computing played a vital role in breaking German codes during the Second World War. Joel Greenberg deciphers the brilliant but troubled life of Alan Turing…

In September 1939, just as the Second World War was declared, a young man arrived to stay at the Crown Inn in the hamlet of Shenley Brook End, Buckinghamshire. He was fit enough – an exceptional long-distance runner, in fact – and his new landlady, Mrs Ramshaw, voiced concerns that such a clearly able-bodied young man wasn’t doing his bit for the war effort by joining up.

Mrs Ramshaw’s indignation couldn’t have been more misplaced. The man was Alan Turing, and his work at nearby Bletchley Park – the secret base of the Government Code and Cypher School (GC&CS), the Foreign Office’s codebreaking section – was to prove crucial in thwarting German military actions.

Turing had returned to England the previous summer after several years of research at Princeton University, which led to his PhD. The University of Cambridge then renewed his fellowship at King’s College, to which he had first been elected in March 1935 after earning a first-class honours degree there.

In 1938, with the threat of conflict in Europe looming, Turing was among a number of British academics approached by GC&CS to undertake secret work for them in anticipation of the outbreak of war. He worked part-time for GC&CS, attending several training courses, and collaborated with Dilly Knox, a veteran First World War codebreaker, on attempts to break the Enigma machine.

Alan Turing and Bletchley Park

On 4 September 1939, the day after Britain declared war on Germany, Turing reported for duty at Bletchley Park and stepped up his work on Enigma. He would go on to lead the team named Hut 8, after the wooden hut in which it was initially based.

Contrary to popular belief, there was no single ‘Enigma code’. The Enigma machine – actually a family of portable encryption devices that substituted each letter of a message for another letter of the alphabet – was first developed in the 1920s and enhanced over subsequent years. By the late 1930s different versions were used by the various branches of the German military. The Germans’ operating procedures exploited the reciprocal nature of the machine. When two Enigma machines were set up the same way, if on one you typed ‘A’ and it turned it into ‘B’, on the other machine if you typed ‘B’, it would turn it into ‘A’.

The setting that governed these substitutions was known at Bletchley Park as the daily key, because it was usually changed every 24 hours. If the Bletchley Park codebreakers could work out the daily key, they could decrypt and read all of the intercepted German messages sent that day. This was done using replica Enigma machines, manufactured in Britain. But the number of possible daily keys was almost too big to imagine. In the case of the German army and air force Enigma, there were 158.9 million, million, million possibilities. It was this daily key that Turing and his colleagues were trying to work out.

In the preceding months, Knox had met with members of the Polish Cipher Bureau who were collaborating with French intelligence. Having worked on Enigma for several years, the Poles had enjoyed some success in breaking the system used by the German army and air force in the 1930s, but their methods no longer worked because of changes made to Enigma by the Germans. They had also designed a semi-automatic machine – a bomba kryptologiczna (reputedly named after a Polish ice cream dessert called a bomba) – to determine the settings that were vital to deciphering the codes produced by Enigma, hugely speeding up the process. In July 1939, they shared their findings with Knox.

Did Alan Turing break Enigma?

At Bletchley Park, Turing devised a new and more powerful kind of electro-mechanical machine for determining the crucial Enigma settings. Another Cambridge mathematician working at Bletchley Park, Gordon Welchman, made a crucial addition that increased the effectiveness of the machine – called the Bombe – providing Bletchley Park with a vital codebreaking tool. By the end of the war, some 211 machines had been produced.

The Bombe, though, wasn’t the complete solution to Enigma. Early in 1940, Turing was asked to take on the task of breaking the German navy’s Enigma system, which used more secure procedures than those of the air force and army. Many at Bletchley believed it could not be broken – yet doing so was vital.

These were desperate times for Britain. The country became increasingly dependent on convoys of ships carrying vital supplies across the North Atlantic, and German U-boat attacks were wreaking havoc on these convoys: average monthly shipping losses in 1940 exceeded 220,000 tonnes. To tackle this, Turing’s Bletchley Park team was expanded.

The challenge was this. Having set up their machines using the daily key, each Enigma operator applied one final setting before encrypting a message. The operators for the German army and air force were allowed to choose this setting themselves, but the German navy issued code books for this purpose. In a remarkable piece of work, Turing managed to deduce, quite quickly, how these code books were being used, but realised that his team would need to acquire copies before further progress could be made.

It wasn’t till a German naval code book was captured that Turing and his colleagues began to achieve success in working out the daily key and reading encrypted German naval messages. Intelligence reports about Germany’s U-boat and ship movements could then be produced and sent to the Admiralty for dissemination.

The interception and decryption of German naval messages played a crucial role in the great sea battles of the Second World War. German ships and U-boats could be located and attacked, and Allied convoys could be diverted to reduce shipping losses.

At its peak, Hut 8 had more than 150 staff. It was part of a large codebreaking operation at Bletchley Park that broke a number of other enemy code and cipher systems as well as Enigma, and employed as many as 10,500 people – the operation truly was a team effort. Yet Turing’s contribution was fundamental.

In late 1940 Turing wrote a report describing the methods he and his colleagues were using to solve the German Enigma system. It was known as ‘Prof’s Book’, and it became essential reading for new recruits.

Alan Turing’s legacy

Years later, Bletchley Park codebreaker Peter Hilton explained that what set Turing apart from his colleagues was his ability to come up with ideas that Hilton felt he would not have thought of “in a million years”. These ideas gave rise to a number of statistical methods with colourful names such as ‘Banburismus’ and ‘Turingery’.

In June 1946 it was announced that Turing had (in 1945) been awarded the Order of the British Empire (OBE) for war services. There were rumours that he had been considered for a higher award, but that the OBE was the highest that could be awarded to civil servants of Turing’s official wartime rank – his true role not being revealed for another three decades.

After the war, Turing worked at the National Physical Laboratory in London, where he designed an early digital computer. In 1945, he took up a position at the University of Manchester and contributed to its pioneering computer developments. Biological research was now occupying much of his time and in November 1951 he completed a paper on morphogenetic theory. However, it was work he’d undertaken much earlier that brought him academic renown in later years.

In 1935 Turing had attended a lecture by mathematician Max Newman, discussing the Entscheidungsproblem (‘decision problem’) which asks for a way of determining which mathematical problems are computable. This had intrigued Turing, and his research yielded the paper ‘On Computable Numbers with an Application to the Entscheidungsproblem’, published by the London Mathematical Society in 1937. By the early 1950s, his fame as the author of ‘On Computable Numbers…’ was growing, and in 1953 the University of Manchester appointed Turing to a specially created readership in the theory of computing.

But while Turing’s academic renown was growing, his private life was in turmoil. On 31 March 1952 at a court in Knutsford, Cheshire, Turing was charged with being “party to the commission of an act of gross indecency” – in effect, he was charged with being homosexual. He pleaded guilty. Instead of imprisonment he opted for hormone ‘treatment’ – oestrogen injections that made him put on weight and enlarged his breasts.

How did Alan Turing die?

On the morning of 8 June 1954, Turing was found dead in bed by his housekeeper. The coroner’s verdict found that he had taken his own life there were reports that a partly eaten apple by his bed contained traces of cyanide.

It was not till many years after the publication of Turing’s 1937 paper that it became clear it had probably laid the foundations for the evolution of computing. His story has now been told on stage and screen perhaps not surprisingly, he remains the only Bletchley Park figure to be widely known. Yet it was only after his death that much of Turing’s life and work, obscured for so long, was revealed.

Joel Greenberg is the author of Gordon Welchman: Bletchley Park’s Architect of Ultra Intelligence (Frontline, 2014)

7 things you didn’t know about Alan Turing and Bletchley Park

The Buckinghamshire estate of Bletchley Park was Britain’s primary decryption establishment during the Second World War. Home of the Government Code and Cipher School (GC & CS) – the forerunner of today’s GCHQ – operations at Bletchley are said to have shortened the Second World War by as many as two or three years. But how much do you know about the history of Bletchley Park and its most famous codebreaker, Alan Turing? Here are seven surprising facts…

Bletchley was an early GCHQ

Bletchley Park was the wartime home of the Government Code and Cipher School (GC & CS). Formed after the First World War from the codebreaking facilities at the Admiralty and the War Office, by 1939 GC & CS was part of the Secret Intelligence Service (SIS or MI6), itself within the Foreign Office.

Bletchley was female-friendly

Bletchley drew together a wide mixture of civilian and service personnel in what was effectively a ‘green field’ organisation. It moved from being simply a codebreaking operation to a more integrated signals intelligence entity, linking interception, cryptanalysis, translation, intelligence analysis and intelligence dissemination. This worked on a factory-like basis to produce a continuous flow of useable intelligence.

At its height in 1944, Bletchley Park employed close to 10,000 people, up to three-quarters of whom were women, performing a wide array of tasks.

Bletchley was top-secret

Christopher Grey, professor of organisational behaviour at Warwick University, says: “What had been created was no less than an intelligence ‘factory’ which sucked in thousands of people working in conditions of complete secrecy. Everyone employed at Bletchley Park was told that they must never reveal anything of their work. Many had no idea what they were working on – they merely knew that they had to complete their one little part of the process.”

Bletchley shortened the war

It is sometimes said that the operation at Bletchley shortened the Second World War by two or three years, “and it is certainly easy to see how reading so many of the operational and strategic signals of the enemy was invaluable to the Allies”, says Christopher Grey.

Bletchley’s most famous codebreaker is Alan Turing

Born in 1912, Turing studied mathematics at King’s College and afterwards he completed his PhD at Princeton in the US. His thesis was ‘Systems of logic based on ordinals’. Turing’s most important theoretical work ‘On computable numbers’ was written in 1936. This essentially founded modern computer science.

Turing arrived at Bletchley in 1939 and soon became the head of the Naval Enigma Team. He played a vital role in breaking German codes during the Second World War, working with a team of colleagues including Dilly Knox, who had broken an Italian naval enigma cipher as early as 1937. In 1945, Turing was awarded an OBE for his wartime services. But, Christopher Grey stresses, “it certainly wasn’t the case that Turing alone cracked Enigma, any more than there was a single Enigma to be cracked”.

The ‘father of modern computing’

Turing gave the earliest known lecture to mention computer intelligence in 1947. He is considered the ‘father of modern computing’. Turing’s article ‘Computing machinery and intelligence’, led to what is now known as the Turing Test. This test examines a machine’s ability to demonstrate intelligent behaviour equivalent to or indistinguishable from a human.

Turing’s article ‘The chemical basis of morphogenesis’, published in 1952, anticipated the field now known as artificial life.

‘Gross indecency’

On 31 March 1952 at a court in Knutsford, Cheshire, Turing was charged with being “party to the commission of an act of gross indecency”. He pleaded guilty. Instead of imprisonment he opted for hormone ‘treatment’ – oestrogen injections that made him put on weight and enlarged his breasts.

On the morning of 8 June 1954, Turing was found dead in bed by his housekeeper. The coroner’s verdict found that he had taken his own life there were reports that a partly eaten apple by his bed contained traces of cyanide.

With special thanks to experts from Bletchley Park, who contributed facts about Alan Turing ahead of the release of the 2014 film The Imitation Game

Beating Enigma

Modern computers were sci-fi fantasy during World War II but the devices developed for codebreaking at Bletchley Park led the way to the computers we’re used to today. The Germans were using a device called Enigma, which let them encrypt their communications. If you knew how the device worked and you knew the starting settings, you could decode a message. However, there were millions of potential starting positions so it was extremely difficult to decode by hand though many did just that for years.

Back in 1932, the Polish Cipher Bureau revealed that they had broken the first German Enigma messages. Their cryptologists reverse-engineered the Enigma machine and these advancements eventually led to the “bombe”, an early computer that could figure out potential starting settings for Enigma messages much faster than any human could. Alan Turing is one of the people famous for the great work developing the bombe.

Sadly, the bombe didn’t work by itself. You couldn’t just click a button and let it do its thing. It was a very hands-on device that most people would barely recognise as a computer. People needed to be brought in to operate the machine. Even then, the bombe didn’t decode the messages itself. It identified wheel orders that were possible, reducing the potential work for the codebreakers further down the line. So Bletchley Park needed cryptologists, bombe operators, codebreakers, translators, cooks, cleaners, drivers… and they all had to work in absolute secrecy.

31 Beguiling Facts about Bletchley Park

Bletchley Park remains one of the most popular British tourist attractions for many reasons. To this day, you can still head to the site to learn more about how codes were intercepted and cracked, as well as to find out tons of secrets about the very first computers.

How much do you already know about Bletchley Park? Regardless, it’s time to crack on with interesting facts about Bletchley Park to clue you in. Cracking codes was a matter of life and death back then – meaning it’s well worth celebrating the efforts of the brave men and women who once worked there.

  1. Bletchley Park is situated in Milton Keynes, in the county of Buckinghamshire, England.
  2. It is now a heritage site due to its fame as being the home of Government employed personnel engaged as ‘Code Breakers’ during World War II.
  3. The Mansion House of Bletchley Park was built in 1883 and is surrounded by landscaped gardens and some woodland.

  1. The house was constructed in the Gothic and Tudor style.
  2. After the war, Bletchley Park became a Management Training Facility for the Post Office.
  3. During the war, bespoke machinery was designed and built to aid decryption of the codes vital to provide information for military tactical planning.
  1. The work of the team at Bletchley Park, led to the development of Colossus – the name given to the world’s first electronic digital programmable computer. We owe Colossus an awful lot – you wouldn’t be reading this fact file without its work, for example!
  2. Government War operations at Bletchley Park remained ‘classified’ until 1970. This means you’re now freely able to pore through and enjoy some of the most fascinating secrets of the period!
  3. The National Museum of Computing is now housed at Bletchley Park in a separate building. A model of the Colossus is exhibited there.

  1. A model of the ‘Bombe’ is also on display. This iconic computer was designed by Alan Turing and refined by Gordon Welshman, who were employed as ‘code breakers’ at Bletchley Park.
  2. The ‘Bombe’ is a large machine containing 10 miles of wire,100 rotating drums and an impressive 10,000,000 solders!
  3. The first operational ‘Bombe’ used at Bletchley Park was nicknamed ‘Victoria’ and began working on March 14th, 1940.
  4. 211 ‘Bombe’ decoder machines were in use by the end of the Second World War. They were a huge support in helping to turn the tide against Nazi Germany.
  5. On January 20th, 1940, the German method of sending coded messages, a system called the ‘Enigma’ code, was successfully broken at Bletchley Park. This is an achievement widely regarded as one of the biggest non-battle successes of World War II.
  6. The team working on Enigma were under the supervision of Dilly Knox, and included Alan Turing, Peter Twinn and John Jeffries.

Plugboard of an Enigma machine. During World War II, ten plugboard connections were made.

  1. De-coders at Bletchley Park are credited with ‘breaking’ the codes of several countries, who were using them for hostile war purposes. Namely, codes cracked here belonged to Germany, Italy, and Japan.
  2. Thousands of messages passed through decryption at Bletchley Park. Some were false – and all needed verification of authenticity.
  3. The decoding and detailed study of information derived from coded messages means Bletchley Park is credited with shortening the Second World War by at least two years.
  4. It’s also credited with saving many lives as well as preventing many serious injuries.
  5. Bletchley Park Mansion and Huts on the land, which formed part of the accommodation used during the war effort, were due to be demolished. Initially, the local council decided that the unkempt Mansion and decaying huts should be replaced by a supermarket and shops.
  6. The decision to remove Bletchley Park buildings to make way for development was halted when the Post Office agreed the land be sold. Peter Wescombe, Founding Member of the Bletchley Park Trust, used an £8 million grant from the Heritage Fund to update the site for it to become a Museum and Visitor Centre.

  1. In 2013, having been hidden for 73 years, some workmen found papers stuffed into a box in the roof of one of the huts.
  2. Some of these documents remain in fragments, but they are proof of methods used to break codes. One such precious document displayed is titled the ‘Blist’. It is dated April 14 th , 1940.
  3. The National Radio Centre is housed at Bletchley Park. The NRC exhibits documents and articles tracing the history or radio communication.
  4. The NRC is somewhat unusual in that it is open seven days per week,52 weeks per year with the exception of Bank Holidays.
  5. The National Museum of Computing opened in 2007 to collect, restore and exhibit computers and material relevant to the codebreaking history of the location.
  6. The National Museum of Computing receives no public funding – it relies entirely on donations!

‘Christopher’ in ‘The Imitation Game’ – Turing’s re-built bombe machine displayed at Bletchley Park Museum


Play How an Enigma machine works

Peter Westcombe, founder of the Bletchley Park Trust, explains in detail how the Enigma machine works and how its codes were broken by the code-breakers at Bletchley Park.

Peter Westcombe, founder of the Bletchley Park Trust, explains in detail how the Enigma machine works and how its codes were broken by the code-breakers at Bletchley Park.

Play Fiona Bruce talks to a Bletchley Park code breaker

Fiona Bruce talks to Jean Valentine, a Wren who worked as a code-breaker at Bletchley Park during the war.

Fiona Bruce talks to Jean Valentine, a Wren who worked as a code-breaker at Bletchley Park during the war.

Play How Alan Turing broke the Enigma codes

Fiona Bruce describes the complexity of the Enigma codes and explains how they were cracked by the master code breaker Alan Turing.

Fiona Bruce describes the complexity of the Enigma codes and explains how they were cracked by the master code breaker Alan Turing.

Play The code breaking that changed the war

Simon Greenish, director of Bletchley Park, describes the role that the Bletchley Park code-breakers played in changing the course of the war.

Simon Greenish, director of Bletchley Park, describes the role that the Bletchley Park code-breakers played in changing the course of the war.

Play The world's first computer

Fiona Bruce describes how volunteers have reconstructed the code-breaking Colossus computer at Bletchley Park.

Fiona Bruce describes how volunteers have reconstructed the code-breaking Colossus computer at Bletchley Park.

'Original material'

Trust chief executive officer Iain Standen said historical integrity was "hugely important" and the buildings were now as near to original as possible.

"Everywhere we can we've used the original material that was here," he said.

Hut restoration was also threatened by the very nature of the centre's war work - secrecy.

With no photographs of the insides to work with, Bletchley Park looked to its most valuable resource - the veterans.

And it is their once silent voices which have allowed the buildings to come alive again.

Their testimonies mean that today's visitors see what each building looked like during the war - right down to the correct paint colour, thanks to a specialist historic paint analysis company.

When you enter a hut, it looks like code-breakers have just left the room.

Alan Turing and the Hidden Heroes of Bletchley Park: A Conversation with Sir John Dermot Turing

Alan Turing helped the British government pioneer the technology to decrypt Nazi Germany’s secret communications during World War II. In 1952, Alan Turing was forced to endure chemical castration by the same government after being prosecuted for homosexual acts. We sat down with Sir John Dermot Turing, Alan Turing’s nephew and author of a new book on Bletchley Park, to discusses his uncle’s role pivotal role in computer science and his persecution for being gay in the 1950s.

The Museum had the pleasure of hosting Dermot Turing at our 2017 Winston S. Churchill Symposium. I got to know him fairly well during the long weekend he visited, through meals, a private tour of our galleries and during the symposium itself.

Dermot Turing is the acclaimed author of Prof, a biography of his famous uncle, The Story of Computing, and most recently X, Y and Z – The Real Story of How Enigma was Broken. He is also a regular speaker at historical and other events. He began writing in 2014 after a career in law. Dermot is a trustee of the Turing Trust. He is a Visiting Fellow at Kellogg College, Oxford.

Dermot has a new book out, with the paperback version available in the United States in July 2020, titled The Codebreakers of Bletchley Park: The Secret Intelligence Station that Helped Defeat the Nazis. I asked him some questions about the book, Bletchley, and his war-winning, world-famous uncle.

Dermot, thank you for agreeing to this interview. I believe most readers will know the overall significance of Bletchley Park and how it was “the Goose that laid the Golden Eggs” in terms of Allied intelligence against Nazi Germany. Tell us about Bletchley as an organization.

Thanks for having me! I think that quote is attributed to Winston Churchill, who had a special box of decrypts delivered to him every day. At first he wanted to see every single decrypted message but rapidly the volume of stuff grew so much for that to be practical, so they just gave him the juicy bits. In typical Churchill fashion he would then surprise his chiefs of staff with things which they probably didn’t know. I’m not sure this is the ideal way to run a war, but that wasn’t your question.

Bletchley Park was a converted private house which was taken over by the British Secret Intelligence Service (MI6 to you and me) in 1938. There was a small code-breaking organization between the wars called the Government Code & Cypher School, which was part of MI6, and they moved in just before the war began. In the months before then, GC&CS had been out recruiting extra staff to put on their ‘emergency list’—effectively a reserve list. On the list were 24 academics from Cambridge and 13 from Oxford, and a handful of others, but it gives you an idea of the sort of people they thought would be useful. Alan Turing was one of these academics: he was recruited in 1938 and sent on a training course to learn about codes (and the Enigma machine) early in 1939.

In the early days the total complement was a couple of hundred or so, but the success of the codebreaking effort was so great that the number of people grew enormously, to a peak of around 10,000 in 1944. That meant that Bletchley Park itself was a building-site for much of the war, as new buildings had to be constructed to house all these extra folks.

I recall when you visited, one of the key points you stressed in private and during your public presentation was that Alan Turing didn’t do this all on his own. You felt a bit remiss that so many went unacknowledged as your uncle received all of the praise. Was that the motivation of this book?

Certainly that was part of it. It’s not just that Alan Turing seems to scoop up all the praise, but that there were so many other interesting characters at Bletchley it would be good to bring some of them to the fore and have their stories better known. The challenge for a writer is then how to fit dozens of biographies together without making it too dense and tedious to read. People want to read stories, but the story of Bletchley Park is a great one, so the solution was to use the narrative of what happened at Bletchley as a framework within which to talk about the people who worked there.

Tell us about the people—countless people—who played important parts to making Bletchley Park a success. What were their backgrounds, their lives during the war?

Well, as I mentioned, at the very beginning the recruitment was mainly focused on the academics at Oxford and Cambridge. The head of GC&CS, Alastair Denniston, referred to them as ‘men of the professor type,’ which is rather a quaint expression, but it gives a good flavor of it. There weren’t many women on his list, but one of the interesting things is that that changed during the course of the war. By the middle period of the war, when the bombe machines used in decrypting Enigma were up and running, Bletchley needed huge numbers of junior staff for fairly routine roles. A lot of these were from the Women’s Royal Naval Service (the Wrens)—you have a similar story in the US where the American bombe machines in Washington were tended by WAVES.

So, we have a traditional picture of Bletchley being staffed by tweedy professors who smoked pipes and teenage Wrens doing mind-numbingly boring jobs, but actually it turns out to be more complicated than that. For one thing, quite a large number of women were employed in senior code-breaking and intelligence analysis jobs. It’s difficult to be sure, because it was the 1940s, and in those days, roles were theoretically segregated by gender, and there were no women’s grades for codebreakers and analysts—so they had to be called ‘clerical’ or ‘translator’ or whatever, regardless of what they were actually doing. It’s quite hard to figure out from the documents what the true picture was. But we do have the accounts of the codebreakers themselves, and it’s quite clear that a large cohort was recruited from women’s colleges to do the same sort of jobs as the men.

Why do you think that they went uncelebrated for so long?

Ah, well, this is all about secrecy. When people arrived at Bletchley Park for the first time, there was a special ceremony where the importance of secrecy was drummed into their heads, and they were made to sign a document based on the Official Secrets Act, which said that severe criminal consequences would happen if anyone ever disclosed anything about what happened at Bletchley Park. And in case anyone was in any doubt about it, at the end of the war the head of Bletchley Park sent round a memo telling everyone that the code of silence applied not just during wartime but forever.

So, nobody was allowed to talk about what they had done until many years afterwards, when the UK Government slowly began to relax the restrictions in the late 1970s. Of course, there were some leaks and some spies, and the extent to which the secrecy surrounding Bletchley was not completely watertight is interesting. Another thing of interest is how it came about that the story of Bletchley Park eventually became public—all that is explored in the book as well.

Of all the people who served at Bletchley, your uncle, Alan Turing, is by far the most famous. Tell us about his wartime contributions, what he thought of his work, and what he thought of his own significance.

One of the curious things is that Alan Turing is so closely identified with Bletchley Park, and in particular with the cracking of the Enigma cipher machine. It’s something of a puzzle because he wasn’t a professional codebreaker and his role at Bletchley Park was actually much more limited than people might imagine. Yes, it’s true that he was instrumental in designing the bombe machine on which the breaking of Enigma depended, and he was quite heavily involved in the attack on Naval Enigma in the early years of the war. But by 1942 the codebreaking process, certainly on Enigma, was largely mechanized, so there was much less for him to do in the theoretical line. So then he was sent over to America to advise on the development in Dayton, Ohio, of the US Navy’s bombe machine, and to inspect various secret encryption devices being built at Bell Labs in New York. One of those was a huge thing for enciphering phone-calls, so that Franklin D. Roosevelt and Winston Churchill could speak freely without the Germans listening in. After that, Alan Turing was only rarely at Bletchley Park, because he was working on his own speech encipherment device. For him, I think the codebreaking was a bit of an interlude in his career as a mathematician and computer scientist, and he would have been eager to deny that his own role at Bletchley was unduly significant.

So, if you look at his contribution in that context, it was quite limited in terms of scope and the amount of time he spent on codebreaking but on the other hand, it was enormous, in terms of the sheer volume of decrypts and intelligence that came out of the processing of Enigma as a result of his invention of the bombe machine. I suspect that underneath this paradox it is the story of Alan Turing himself which people find fascinating and that is why we tend to inflate his importance as a code-breaker.

As a family member, what insights have you gleaned, either from family papers or lore over the years?

Well, of course there is nothing about the Bletchley years because of the Official Secrets Act, except for anecdotes. My father (Alan’s older brother) used to talk about Alan cycling to work in the summer wearing his gas-mask because it warded off hay-fever, and of course that scared the pants off the people who saw him, who thought there must be a raid on. And then there was the time when there was an inter-service athletics meeting and this civilian apparently called ‘Professor Turing’ asked to participate (he wasn’t a professor but that was his nickname). So of course all the super-fit army and navy men had a good laugh thinking about this professor chap who would be left well behind them all. What they didn’t know was that Alan Turing was an Olympic-level runner and of course it was the Prof who beat the army and navy guys by some margin.

My own view from the people I spoke to who knew Alan and worked with him is that Alan Turing may have been eccentric, but a rather different and more human character than the asocial individual that he might seem to be from some portrayals in the movies.

Alan Turing had perhaps the most disparate difference between war time significance and post-war celebrity. This includes his prosecution under the British anti-homosexual laws and his terribly depressing death. Can you comment on this?

Yes, this is a very perceptive question. In his lifetime of course nobody knew, and nobody was allowed to know, about what had happened at Bletchley Park. But nevertheless Alan Turing was in a small way something of a minor celebrity because of his post-war work building the earliest British computers. You know, the media called it the ‘artificial brain,’ it was all over the papers and the BBC and there was a hoo-hah about whether ‘machines can think,’ and Alan Turing was at the center of all that. So there is a possibility that the reason Alan Turing got prosecuted for homosexual activity was connected with his being a semi-high-profile individual. In ordinary cases—and there were literally dozens of these in the courts at the time, this is the early 1950s—there would be one count on the indictment, but in Alan’s case there were six counts each against him and against his partner. I can’t explain that otherwise than that the police were out to get him in some sense.

But actually the myth can get in the way of reality at this point. We have this idea that Alan Turing was hung out to dry by the British Establishment and that his conviction and treatment led directly to his suicide two years later. In fact it’s more complicated than that. To start with, his ex-colleagues from Bletchley Park came to speak for his defense at the trial, and their testimony explained—without giving away any secrets—how significant Alan’s wartime contribution had been, and I think it was their intervention which stopped Alan going to prison or getting a formal criminal record (which would have cost him his job.)

The treatment he received was not the idea of the Establishment as such but the result of the rather bizarre way that homosexuality was regarded as a disease in 1950s Britain, and Alan was handed over by the court to the medics and psychiatrists. I reckon he took all that in his stride, and in fact it’s quite hard to find any causal links between his treatment, which finished in 1953, and his death in 1954.

What is the legacy of Bletchley Park, Alan Turing, and those unsung heroes that worked with him?

In Britain, people are immensely proud of Bletchley Park and its achievements. The idea that the war was won not just on the battlefield but also by brainpower and that the enemy was defeated intellectually as well as physically is very appealing. There’s also the fact that the origins of computing lie in the machines used to attack ciphers, and of course the present-day relevance of encryption to secure communications means that code-breaking and security are enduring concepts.

But visitors to Bletchley Park want to know a bit more than the technicalities of code-breaking, Enigma machines and so forth—it’s people stories that chime best. So visitors want to find out about everyday things like what the food was like and what happened to the codebreakers when the war ended. Some of them became famous in other contexts—politicians, academics, writers and so on—and some stayed on and worked for what is now GCHQ but a lot of the women at Bletchley went back into civilian life and to all intents and purposes disappeared. That’s something which interests me, because it symbolizes what happened to a lot of women who discovered something about their abilities and personalities during the war years, but after the war the men took back the significant roles and many successful women found themselves sent back to the kitchen. We can learn about the social side of things as much as the intellectual side.

Thank you very much for sharing these thoughts with us.

No, thank you for the opportunity. I’m looking forward to my next visit to The National WWII Museum!

Recent History

With the declaration of peace, the frenzy of codebreaking activity ceased.

On Churchill’s orders, every scrap of ‘incriminating’ evidence was destroyed. As the Second World War gave way to the Cold War, it was vital that Britain’s former ally, the USSR, should learn nothing of Bletchley Park’s wartime achievements.

The thousands who had worked there departed. Some continued to use their remarkable expertise to break other countries’ cyphers, working under a new name: the Government Communications Headquarters (GCHQ).

The site became home to a variety of training schools: for teachers, Post Office workers, air traffic control system engineers, and members of GCHQ. In 1987, after a fifty-year association with British Intelligence, Bletchley Park was finally decommissioned.

For decades, the codebreakers would remain silent about their achievements. It was not until the wartime information was declassified in the mid-1970s that the truth would begin to emerge. And the impact of those achievements on the outcome of the war and subsequent developments in communications still has not been recognised fully.

Reader Interactions


Have visited twice, it is wonderful, interesting place. Just gets better. Loved the work done on hut 6, my Mum worked there. Will go back if possible next time I am in England.

The two other people associated with Bletchley Park who ought to be much better known are Max Newman and Tommy Flowers who were the main drivers behind designing and building the Colossus computer that decrypted the ciphers produced by the German Lorenz machine. As I understand it, though Turing and Twin did amazing work to crack the Engima cipher, it was cracking the Lorenz cipher that was the ultimate prize, and made the major contribution to shortening the war. This is because the Germans mainly used Enigma for tactical communications between units within the individual forces (Army, Navy and Luftwaffe). In contrast, the Lorenz machines were used for top level strategic communications between Nazi High Command and the German forces it was correspondingly a much more complex cipher to crack, and so an automated, computer-driven approach was the only viable one in the long term.

The Allies’ ability to decipher many of the Nazi’s strategic communications was crucial to the war effort. For example, alongside the D-Day preparations, a dummy preparation site was set up in Eastern England, designed to fool the Nazis into thinking an attack on Europe was going to be mounted on the Calais region of the French coast. Bletchley Park intercepted, and decrypted using Colossus, a high level Lorenz message that confirmed the Nazis did indeed think that an Allied landing attempt would be made at Calais. So when the D-Day fleet sailed, the Allies were pretty confident that Hitler would be taken by surprise!

And of course, we mustn’t forget that many of the production Colossus machines were assembled in the USA!

Thank for this interesting and historical information.

We visited Bletchley Park and loved it! What a great part of our history that is shared with those who were allies. Awesome experience!

my mum wynona was picked to go there during WW11 to learn deciphering. Apparently she was in the number 16 in line and just missed out by 5 other girls, she spent several weeks there and then went onto being a WREN at Grave’s End helping to bring in the ships through the channel at night-time.

very interesting article: however there are several small typo errors. Also, it’s Domesday book, not “doomsday”
It is ironic that so much death and destruction facilitated today’s computer technology.

Watch the video: Bletchley.