Bletchley Park

Bletchley Park is an English country house and estate in Bletchley, Milton Keynes (Buckinghamshire), that became the principal centre of Allied code-breaking during the Second World War. During World War II, the estate housed the Government Code and Cypher School (GC&CS), which regularly penetrated the secret communications of the Axis Powers – most importantly the German Enigma and Lorenz ciphers. The GC&CS team of codebreakers included John Tiltman, Dilwyn Knox, Alan Turing, Harry Golombek, Gordon Welchman, Hugh Alexander, Donald Michie, Bill Tutte and Stuart Milner-Barry.

The team at Bletchley Park, 75% women, devised automatic machinery to help with decryption, culminating in the development of Colossus, the world's first programmable digital electronic computer. Codebreaking operations at Bletchley Park ended in 1946 and all information about the wartime operations was classified until the mid-1970s. After the war it had various uses and now houses the Bletchley Park museum.

It was first known as Bletchley Park after its purchase in 1877 by the architect Samuel Lipscomb Seckham, who built a house there. The estate of 581 acres (235 ha) was bought in 1883 by Sir Herbert Samuel Leon, who expanded the house into what architect Landis Gores called a "maudlin and monstrous pile", combining Victorian Gothic, Tudor, and Dutch Baroque styles. After the death of Herbert Leon in 1926, the estate continued to be occupied by his widow Fanny Leon (née Higham) until her death in 1937. In 1938, the mansion and much of the site was bought by a builder for a housing estate, but in May 1938 Admiral Sir Hugh Sinclair, head of the Secret Intelligence Service (SIS or MI6), bought the site for use in the event of war.

Sinclair bought the mansion and 58 acres (23 ha) of land for use by SIS. A key advantage seen by Sinclair and his colleagues (inspecting the site under the cover of "Captain Ridley's shooting party") was Bletchley's geographical centrality. It was almost immediately adjacent to Bletchley railway station, where the "Varsity Line" between Oxford and Cambridge – whose universities were expected to supply many of the code-breakers – met the main West Coast railway line connecting London, Birmingham, Manchester, Liverpool, Glasgow and Edinburgh. Watling Street, the main road linking London to the north-west (subsequently the A5) was close by, and high-volume communication links were available at the telegraph and telephone repeater station in nearby Fenny Stratford. Sinclair bought the park using £6,000 (£484,000 today) of his own money as the Government said they did not have the budget to do so.

Before the site was considered for use by GC&CS, it had been initially selected by Laurence Grand and established to be a school for his own section of the SIS called the Section for Destruction, or Section D, a paramilitary outfit specializing in irregular warfare, guerrilla warfare, and sabotage. This site was selected to be an experimental research and development station and explosives schoolhouse for a rather pyrotechnical team belonging to Section D. Modern sabotage from a scientific approach was a brand new field of science, and Bletchley was only one of many such early locations where new ingenious devices were studied. Grand was asked once to explain the conception behind this outfit, to which his response was: ‘We just want to blow off people’s hats."

They began their programs here on June 15, 1939. The chemical engineer Colin Meek (D/X1), a recent graduate from Manchester University, employee of Imperial Chemical Industries and one of the early members of the team to invent plastic explosives, was selected to train recruits in the composition and usage of demolitions and explosives under the explosives program schoolmaster, Dr. Drane (D/X).

However, when the war officially began, and the codebreakers finally moved in, they constantly complained that the noise of the explosives being tested by Section D made them lose their concentrations. The explosives testing of Section D was then moved to Aston House in November, several months after the codebreakers had set up shop.

Five weeks before the outbreak of war, Warsaw's Cipher Bureau revealed its achievements in breaking Enigma to astonished French and British personnel. The British used the Poles' information and techniques, and the Enigma clone sent to them in August 1939, which greatly increased their (previously very limited) success in decrypting Enigma messages.