One of Turing's most important achievements was creating the Bombe, an electromechanical machine that automated Allied code breaking during the Second World War.

The machine was devised to crack Enigma ciphers used by the German army, navy and air force to protect their communications.

Each day the Bletchley codebreakers were engaged in a race against time to crack that day's Enigma code.

To help with the decryption, Turing designed the Bombe in 1939. Each bombe was built to work as if it were several Enigma enciphering machines wired together and could narrow down the settings used to encrypt each message far more quickly than a human. By the end of the war, more than 200 of the machines were being used in the UK to crack codes.

Photo: Bletchley Park Trust