The English Historical Review Advance Access originally published online on January 13, 2009
The English Historical Review 2009 CXXIV(506):53-93; doi:10.1093/ehr/cen361
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© The Author [2009]. Published by Oxford University Press. All rights reserved.
British Radio Security and Intelligence, 1939–43*
Headingley
Correspondence: e.harrison4472{at}student.leedsmet.ac.uk
There is no previous monograph article on the Radio Security Service [RSS], the British organisation established to intercept the wireless messages of enemy spies during World War Two. This gap can be filled by drawing on private papers and documents in the National Archives from MI5, Bletchley Park, the War Office and the Admiralty. The official historians F.H. Hinsley and C.A.G. Simkins praised RSS efficiency, but MI5 records suggest that while RSS voluntary interceptors were competent, the same was not always true of some other operatives.
The most intellectually outstanding part of the Radio Security Service was its Analysis Bureau, which became part of Section V of the Secret Intelligence Service [SIS] as Vw when most of RSS was taken over by Section VIII of SIS in 1941. Under Hugh Trevor-Roper's leadership Vw produced analytical reports on Axis Intelligence activities, but Felix Cowgill, the head of Section V, sought to restrict the circulation of these reports and the decrypts of enemy secret service messages which they analysed. The diaries of MI5's Guy Liddell suggest that Cowgill's behaviour was a catalyst for the unsuccessful attempt by MI5 to take over Section V of SIS during 1942.
By 1943 Stewart Menzies, the Chief of SIS, was so impressed by Vw that he made it independent of Cowgill as the Radio Intelligence Service. By the end of 1943 MI5 and RSS interception also achieved a better understanding of their mutual roles. But there was a potential threat to the achievements of British radio security and intelligence from the reports of the Cambridge spies to Moscow.