Francis Birch (cryptographer)

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Francis Lyall (Frank) Birch CMG, OBE (5 December 1889 – 14 February 1956) was a British cryptographer. He was educated at Eton and King’s College, Cambridge. He was awarded an OBE in 1919 and CMG in 1945.

In World War I he was in the RNVR, and served in the Atlantic, the Channel and the Dardanelles before joining the Naval Intelligence Division (Room 40) from 1916 to 1919. He wrote a satirical history of Room 40, Alice in ID25.

He was a Fellow of King’s College, Cambridge 1915–34 and a Lecturer in History at Cambridge University 1921–8.

He left Cambridge for the stage in the 1930s.

He joined the Naval section at Bletchley Park in September 1939, and later became Head of the (German) Naval Section. He had to face the shortage of Bombes to decipher the Naval Enigma, which led to the use of American Bombes via OP-20-G.


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