Cdr. Alastair Denniston, CMG, CBE, RNVR

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Cdr. Alexander "Alastair" Guthrie Denniston

Also Known As: "The Little Man"
Birthplace: Albert Terrace, Dunoon, Argyllshire, Scotland (United Kingdom)
Death: January 01, 1961 (79)
Immediate Family:

Son of Dr. James Denniston and Agnes Buntain Denniston
Husband of Dorothy Mary Denniston
Father of Rev. Robin Alastair Denniston and Private
Brother of William Denniston and Elizabeth Denniston

Occupation: Brittish Codebreaker and first head of the Government Code and Cypher School
Managed by: Private User
Last Updated:

About Cdr. Alastair Denniston, CMG, CBE, RNVR


Alexander "Alastair" Guthrie Denniston CB CMG CBE RNVR (1 December 1881 – 1 January 1961) was a British codebreaker in Room 40, first head of the Government Code and Cypher School (GC&CS) and field hockey player. Denniston was appointed operational head of GC&CS in 1919 and remained so until February 1942 Wikipedia: Alastair Denniston

Commander Alexander Guthrie Denniston is the first child and eldest son of James Denniston, Doctor of Medicine, and his wife, Agnes Buntain Guthrie. He was born at Albert Terrace in Dunoon, Scotland, at 08.30 hours on the 1 December 1881 [Registrar General for Scotland, New Register House, Edinburgh, Statutory Register of Births for 1881, registration district 510/1 (Dunoon, Argyllshire), entry number 175. Research by Neil Reid Ford].


He studied at the University of Bonn and the University of Paris.

Sporting Achievement

Commander Alexander Guthrie Denniston was a member of the Scottish men's hockey team that won a Bronze Medal at the Olympic Games in London in 1908. The hockey event took place at White City Stadium, a few months after the main Olympics events. Wikipedia: Alastair Denniston


In 1914 he helped form Room 40 in the Admiralty, an organisation responsible for intercepting and decrypting enemy messages. In 1917. After World War I, Room 40 was merged with its counterpart in the Army, MI1b, to become the Government Code and Cypher School in 1919. Denniston was chosen to run the new organisation. On 26 July 1939, just five weeks before the outbreak of World War II, Denniston was one of three Britons (along with Dilly Knox and Humphrey Sandwith) who participated in the trilateral Polish-French-British conference held in the Kabaty Woods south of Warsaw, at which the Polish Cipher Bureau initiated the French and British into the decryption of German military Enigma ciphers. With the outbreak of World War II in 1939, GC&CS greatly expanded and relocated to Bletchley Park. In February 1942, GC&CS was reorganised, and Denniston was placed in charge of a civil and diplomatic division in London, while Edward Travis succeeded him at Bletchley Park, overseeing the work on military codes and ciphers. Denniston retired in 1945 and later taught French and Latin.

Honours and Awards

OBE. On 7 January 1918 he was appointed an Officer of the Order of the British Empire CBE. On 2 January 1933 he was appointed a Companion of the Order of the British Empire CMG. On 12 June 1941he was appointed a Companion of the Order of St Michael and St George.

Marriage and Children

Alexander Guthrie Denniston married Mary Gilliat, who worked with him in Room 40 at the Admiralty, and they had two children (1) Robin Alastair Denniston (2) Margaret Denniston.

Biographical Account

Wikipedia: Alastair Denniston

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Cdr. Alastair Denniston, CMG, CBE, RNVR's Timeline

December 1, 1881
Dunoon, Argyllshire, Scotland
December 25, 1926
January 1, 1961
Age 79