This is a colourful and authentic account of daily life and work at Government Communications Headquarters, Bletchley Park, the most successful intelligence agency in history.
By 1942 the codebreakers of Bletchley Park and its out-stations were breaking some 4,000 German signals a day, and almost as many from Italy and Japan, eavesdropping on enemy communications up to the highest levels of command. Their colleagues used these decrypts to produce Ultra intelligence which gave a detailed, accurate, and up-to-date picture of enemy strengths, weaknesses, and intentions. The codebreakers' contribution to the war effort was invaluable: Churchill described them as the `secret weapon' that `won the war'.

For the first time a group of the men and women who worked on this top-secret enterprise have combined to write their story in full. Here, they vividly describe their recruitment and training, their feelings and activities, and recall in detail their successes and failures.