The work done at Bletchley Park was highly secret. Much of what was done at Bletchley Park during World War Two remained secret for several decades after the war ended and it was only in 1974 that the public was given greater access to what was done and achieved at this non-descript mansion house in Buckingham, fifty miles to the north of London.


Bletchley Park was purchased by the government in 1938 to house the Government Code and Cypher School. It was run by the Secret Service and commanded by Commander Alastair Denniston. Bletchley Park was barely suitable for its task and many worked in an environment that could only be described as basic. Even one of the centre’s chiefs worked in a child’s nursery – complete with ‘Peter Rabbit’ wallpaper. The house itself was too small to accommodate all those who worked there and many worked in huts dotted around the main house. Each hut had its own specialisation – the Luftwaffe, ‘U’-boats, the SS etc.


Bletchley Park was Britain’s top code-breaking centre and was credited with shortening World War Two in Europe. Few dispute that the work done there was of the utmost importance. Security was ultra-tight and it had to be. A long chain-link fence topped with barbed wire surrounded ‘BP’. The government’s greatest fear was that a Nazi agent would infiltrate the centre and ruin everything the code-breakers at ‘BP’ achieved. Security was so great there that a story is told that a married couple – sworn to secrecy – never knew until the 1970’s that they were both code-breakers at Bletchley Park at the same time.


The work done at Bletchley Park is now well known. Hollywood has made films about it. Brilliant mathematicians recruited from Oxford and Cambridge Universities created pioneering computers that decoded encrypted German military communications. One of the originals at Bletchley Park was Keith Batey, a mathematician at Cambridge University. Batey , two Cambridge colleagues and chess champion Hugh Alexander, were shown an Enigma machine, told how it worked and were then instructed to crack its codes.


The German’s ‘Enigma’ machine puzzled many at Bletchley Park because of its intricacies. Berlin considered that the machine was foolproof and that it could not be cracked. ‘Enigma’ potentially had millions of settings. Towards the end of the war, those who cracked ‘Enigma’ were able to send a German secret message to an Allied commander in the field before the intended German recipient received it himself. Therefore Allied military planners in the field could shape their plans accordingly to accommodate what they believed their opposite number was planning to do.


Work at Bletchley Park was done around the clock on eight-hour shifts – 08.00 to 16.00, 16.00 to 00.00 and 00.00 to 08.00. Codes could come in at any time as service operators stationed around the country listened out for German messages also around the clock. When a message got to Bletchley Park, it was colour coded dependent on what branch of the German military it involved. The code was then sent to the relevant hut to be deciphered. Initially the process took time but the use of the Bombe computers meant that most coded messages could be processed in hours. Once broken, the codes were translated into English.


While the work at Bletchley Park is rightly lauded, the people who worked there were not always immediately successful – sometimes with disastrous consequences. Winston Churchill was to later state that the only time he feared that Britain might lose the war was during the Battle of the Atlantic when ‘U’ boats were very successful against Britain’s merchant fleet. In 1942, the Kriegsmarine added a fourth rotor into the Enigma machines they used making their codes far more inaccessible. It took a year for this machine to be cracked – at a time when ‘U’ boat wolf packs were rampant in the Atlantic.


Some ofof Bletchley Park’s more famous workers were Alan Turing, William Tutte, Tommy Flowers and Gordon Welchman – two Cambridge mathematicians. Working together with a team, they designed the Bombe computer. Provided that the hardware of an Enigma machine was known, the Bombe could crack any Enigma-enciphered code. The first Bombe computer was called ‘Victory’.


When the war in Europe ended in May 1945, the work at Bletchley Park was redirected towards the Soviet Union and used during the Cold War.