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The Papers of Alexander Guthrie Denniston

Reference Code: GBR/0014/DENN

Scope and Contents

This collection consists of letters and accounts of Denniston's code-breaking work in Naval Intelligence in both World Wars and of the setting up of Room 40. There are several photographs of Denniston in Naval uniform and some of the Royal Naval College at Osborne.


  • Creation: 1908 - 1979

Conditions Governing Access

The collection is open for consultation by researchers using Churchill Archives Centre, Churchill College, Cambridge.

Conditions Governing Use

Researchers wishing to publish excerpts from the papers must obtain prior permission from the copyright holders and should seek advice from Archives Centre staff.

Biographical / Historical

Alexander (also called Alastair) Denniston was born 1 December 1881. In 1917 he married Dorothy Mary Gilliat and they had two children Robin and Margaret. His first job was Assistant Master at Merchiston Castle School, 1906-1909. Denniston was a member of the Scottish Olympic Hockey team in 1908. He then taught German at the Royal Naval College at Osborne, 1909-1914. He joined the Admiralty Naval Intelligence Division (NID) a few weeks after the outbreak of World War I, working out of Room 40 (or 40 OB and later called ID 25) of the Old Building of the Admiralty. Denniston soon became second in command of Room 40. After the end of the war he became head of Room 40's successor, the Government Code and Cipher School (GC&CS) and he retired in 1945. His wife also worked in Room 40. Denniston became a Commander RNVR in 1917. Denniston died 1 January 1961.


3 archive box(es)

Language of Materials


Other Finding Aids

The collection has been catalogued and copies of the catalogue are available at Churchill Archives Centre, at The Historical Manuscripts Commission and on the Janus website:

Immediate Source of Acquisition

This collection was mainly given to Churchill Archives Centre in September 1980 by Denniston's son, Robin Denniston.

Related Materials

Churchill Archives Centre also holds the papers of Admiral Sir Reginald Hall (GBR/014/HALL), William F. Clarke (ref. GBR/014/CLKE), and the McLachlan-Beesly papers (ref. GBR/014/MLBE).

Related Materials

The official papers are held by the National Archives.


This collection (fonds) level description was prepared by Louise King of Churchill Archives Centre in October 2004 using information from the original catalogue to the papers, and additional information from Who's Who (A&C Black, 1996).


Denniston, Alexander Guthrie, 1881-1961, Intelligence Officer

2004-10-04 17:02:57+00:00
Language of description
Script of description

Repository Details

Part of the Churchill Archives Centre Repository

Churchill Archives Centre
Churchill College
Cambridge Cambridgeshire CB3 0DS United Kingdom
+44 (0)1223 336087