And here is the Enigma machine, the enciphering device used by the Germans to protect their communications.
The cracking of Enigma by Turing and his colleagues at Bletchley Park played a decisive role in turning the tide of the Second World War.
Sinkings of Atlantic shipping convoys fell by 75 per cent after the breaking of the naval Enigma used to protect communications with German U-boats.
The 'Enigma Machine and Bombe machines replace the usual 'Utitlities' squares.
Photo: Bletchley Park Trust