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Fri, 1 Nov 2019
Overview
GCHQ 100th Anniversary

On 1 November 1919 the Army signals intelligence department at M11b and the Naval signals intelligence from the Admiralty’s Room 40 combined to become the Government Code and Cypher School, known as GC&CS. Led by Commander Alastair Denniston, and based at Watergate House in The Strand in London, GC&CS comprised just fifty personnel.

GC&CS relocated to Bletchley Park for the duration of WW2. Once the war was over the newly re-named GCHQ moved to Eastcote. Between 1950 and 1954 the organisation relocated once more to Cheltenham which remains its primary base. On 1 November 2019 GCHQ celebrates its 100th anniversary.

GCHQ 100th Anniversary
1 / 10During the interwar period GC&CS focused some of its workforce on the threat from Bolshevik Russia. In the late 1920s Russia began using one-time pads to encrypt their most important communications. The system involved using a sheet of randomly generated numbers taken from a larger pad which would only be used once. The sheets are disposed of after use, so the existence of one-time pads is rare. This example shows a Foreign Office ‘out’ one-time pad which was declassified by GCHQ in 2008.