Commander Alexander Guthrie Denniston was a Scottish codebreaker, deputy head of the Government Code and Cypher School (GC&CS) and hockey player. Denniston was appointed operational head of GC&CS in 1919 and remained so until February 1942.
- Occupation
- field hockey player, cryptographer, mathematician, spy
- Citizenship
- United Kingdom
- Born
- December 1, 1881
- Died
- January 1, 1961
