A rare German Enigma enciphering machine will go under the hammer today and is expected to fetch up to £60,000.
Built by Heimsoeth and Rinke in 1941, the oak-encased machine which encrypted German codes during the Second World War is the three-rotor version, used between 1938 and 1944.
The estimate for the sale at Bonhams in Knightsbridge this afternoon is expected to be between £40,000 and £60,000.
Patented by HA Koch at the end of the First World War, the device was intended for commercial purposes but by 1939 the majority of Enigma machines had been appropriated for German military use.
The construction of the world's first top secret computing machine, Colossus, at Bletchley Park near Milton Keynes during the war meant the messages scrambled by the Enigma machine could eventually be decoded in under 24 hours.
The fact that the British managed to crack Enigma is credited with shortening the war as the Allies were able to know what the Germans were doing.
Other notable pieces in the auction include a complete set of Enigma rotors, which are estimated to fetch up to £8,000.
