SIS and GCHQ: Putting the 'C' in Codebreaking
During the First World War, both the Admiralty and the War Office ran successful code-breaking organisations. The Admiralty unit was called 'Room 40' (later 'ID25') whilst the War Office unit, after January 19161 was known as 'MI1b'. Following a meeting of the Cabinet Secret Service Committee in 1919 and extensive negotations, a single central organisation, the Government Code & Cypher School (GC&CS), was established to serve all government departments with signals intelligence and advice on the security of their own codes and ciphers. Though most GC&CS staff came from MI1b, the Admiralty insisted that Alastair Denniston from Room 40 should be its head, and that it should be supervised by the Director of Naval Intelligence (DNI), Commodore Hugh Sinclair.
By 1921 it had become clear that there were no important foreign naval and military communications targets and that most of GC&CS's work was against diplomatic telegrams; Foreign Secretary Lord Curzon asked that it be transferred to him2 . The formalities were completed in April 1922, when GC&CS became the responsibility of the Chief Clerk's Department. The Secret Intelligence Service (SIS) had followed a similar post-war trajectory determined by the same Cabinet Secret Service committee, and was now also in the Foreign Office. In September 1923 primary responsibilities for supervision of GC&CS was assumed by Hugh Sinclair, now a Rear-Admiral and the second Chief of SIS.
By 1926 SIS and GC&CS shared Broadway Buildings (54 Broadway, St James's), performing distinct activities and occupying different floors. In his GC&CS role, Sinclair took the title 'Director of GC&CS'. Denniston and his deputy Edward Travis reported to him. Although Sinclair was not involved in the day-to-day operations of code-breaking and construction, he or other senior SIS staff represented GC&CS over matters such as foreign relations and inter-departmental arrangements for radio and cable interception. Senior promotions, financial questions and internal organisation within GC&CS were approved by him. In July 1938 Sinclair purchased Bletchley Park in Buckinghamshire as a wartime evacuation location for both his organisations. Both moved there in August 1939.
Colonel Stewart Menzies, who succeeded Sinclair as C on the latter's death in November 1939, continued throughout the Second World War to lead GC&CS in its major organisational and inter-departmental development. Although GC&CS grew rapidly and was increasingly autonomous, Menzies retained strong personal control.
At the turn of 1941/42 Menzies appointed a former Deputy Director of Military Intelligence to enquire into an Army-RAF conflict about decryption within Hut 3 at Bletchley which handled intelligence reporting from German army and air force 'Enigma' traffic. On the basis of the report, Menzies completely re-structured GC&CS, dividing it between civilian and Service work. The former, much smaller, part was moved away from Bletchley under Denniston as Deputy Director (Civil). The much larger Service part, under Travis as Deputy Director (Service) remained at Bletchley. Early in 1944, under pressure from Cabinet Secretary Bridges, Menzies expanded GC&CS's security resources. A new Deputy Director for communications security was appointed and Travis, soon to be knighted, was upgraded to the title of Director while Menzies' title became Director-General.
In post-war planning in 1945 it was generally agreed that 'C' should continue to supervise both SIS and GC&CS which, from April 1946, formally took the title of Government Communications Headquarters (GCHQ). But this became increasingly difficult. During the war the requirements on the responsibilities of both GC&CS and SIS had expanded enormously while their work, analysis procedures and reporting lines had diverged. Many of GCHQ's activities such as large-scale radio interception, high-speed analytic machinery and massive communications networks had no pre-war parallels.
Menzies continued as 'Director-General' until his retirement in 1952 and the title was retained by his successor, but when the latter retired in 1956 the title and GCHQ role for the Chief of SIS lapsed. An oral tradition recalls the then Director of GCHQ, Sir Eric Jones, ordering that the SIS term Head Office was no longer to be used.
GCHQ, November 2005
Footnotes
1 The War Office unit had other earlier designations; it did not settle to MI1(b) until the Directorate of Military Intelligence was established in January 1916.
2 "The sphere of activity of the School is now purely political, and the intelligence procured has, except in very rare cases, no relation to, and can be of no value to, the Admiralty... I must not be thought to have passed any criticism upon the Admiralty officials who had hitherto managed the School...but they are administering a system which is fundamentally wrong and which, now that war conditions have receded into the background, must be placed upon a sound and defensible basis." Curzon (Foreign Secretary) to Lee of Fareham (First Lord), 26/4/21: TNA HW 3/38.
