I visited Bletchley Park recently, the code/cipher breaking center where the Nazi Enigma cipher machines were cracked. The picture above is a replica of Alan Turing's "Bombe" machine that helped crack the ciphers. About 200 of these were built during WWII, but all were destroyed after the war. Fortunately, the blueprints survived and engineers built this one, and it works! One of the staff demonstrated how it worked. It did not actually decipher the Enigma machine messages, but provided the key to deciphering much more quickly than previous methods.
Below: Statue of Alan Turing at Bletchley Park. Nearby is an apology from Gordon Brown, when he was Prime Minister in 2009, for the government's prosecution and chemical castration of Turing under a now repealed sex crime law.
Work on code and cipher cracking began at the mansion at Bletchley Park (below), a Victorian Era structure built by a London stockbroker. His children sold it to the government in 1939 for 7000 pounds (a helluva lot more then, but still cheap).
The initial staff was about 200.That grew to over 8000 at war's end and many other buildings and huts were built on the grounds. Some of the scenes in film the "The Imitation Game" were shot in the mansion, including the bar scene below.