A rare German Enigma machine used during World War Two will go under the hammer today.
The oak-encased machine, built by Heimsoeth and Rinke in 1941, encrypted German codes and was used between 1938 and 1944.
The three-rotor device will go on sale at Bonhams in Knightsbridge this afternoon and is expected to fetch between £40,000 and £60,000.
HA Koch patented the machine at the end of the First World War and it was initially designed for commercial use but by 1939 the majority of Enigma devices were used by the German military.
The construction of Colossus - the world's first top secret computing machine - at Bletchley Park during the war meant messages scrambled by the Enigma could be decoded within 24 hours.
Britian's ability to decode German messages is credited with shortening the war.
A set of Enigma rotors will also go on sale, they have an estimate of £8,000.