Re-creation of the 'Colosus' computer, Bletchley Park, 1997.
© Science Museum / Science & Society Picture Library
Detail of the 'Colosus' computer's circuitry and pulley system. Bletchley Park was the British forces' intelligence centre during World War II, and is where cryptographers deciphered top-secret military communiques between Hitler and his armed forces. The communiques were encrypted in the Lorenz code which the Germans considered unbreakable, but the codebreakers at Bletchley cracked the code with the help of Colosus.