Alastair Denniston

Commander Alexander Guthrie Denniston CMG CB RNVR was a British codebreaker in Room 40, first head of the Government Code and Cypher School and field hockey player. Denniston was appointed operational head of GCampCS in 1919 and remained so until February 1942.

Denniston was born in Greenock, the son of a medical practitioner. He studied at the University of Bonn and the University of Paris. Denniston was a member of the Scottish Olympic field hockey team in 1908 and won a bronze medal.

Source: Wikipedia