An incredibly rare four rotor Enigma machine used by the Nazis during the Second World War has emerged for sale for £300,000.
The Nazis sent coded messages through the cipher machines to their ships and U-boats to plan devastating attacks on Allied shipping.
The British codebreakers at Bletchley Park, led by Alan Turing, cracked the original three rotor Enigma machines in 1941.
A subsequent dramatic fall in the number of Allied ships being sunk led the Germans to suspect the Enigma had been compromised.
As a result, in February 1942, they introduced a new fourth rotor wheel which multiplied the number of available settings another 26 times.
