The end of Denniston's career, and his legacy

Last Updated: 05 Sep 2017
Denniston was effectively demoted in 1942, but continued to make a major contribution to British Sigint until the end of the war.


He is wearing a suit and tie
Denniston, 1940s. Colourised by Joel Greenburg. By kind permission of Judith Finch, granddaughter
By 1942, it was becoming clear that GC&CS was a victim of its own success. It had grown tenfold since the outbreak of war, and faced a constant struggle to find and manage the equipment, personnel, and accommodation needed to support this scale of operations. An Army audit report carried out that year highlighted Denniston's shortcomings as an administrator - it did not question his leadership - and Menzies as 'C' seized the excuse to impose his own reorganisation on to GC&CS. Menzies became Director General, Travis became Deputy Director (Service), and Denniston Deputy Director (Civil).

Work against Axis military targets continued at Bletchley Park under Travis, while Denniston and the sections responsible for diplomatic and commercial targets moved back to London to offices in Berkeley Street. Here he was able to continue the inter-war success of GC&CS against these targets. It is instructive to read the comments of American visitors to Berkeley Street who were overwhelmed both by the scale of what Denniston was achieving with a small number of staff, and by his willingness to share everything - not just cryptanalytic techniques, but all the tradecraft which he had developed since 1919 - with them. 

By the end of the war, it was clear that he would have no part to play in the future of the organisation. A further reorganisation had cemented 'C' as Director General, with Travis as Director, and Denniston lost in a little box at the side of the wiring diagram. He was encouraged out of the organisation before VJ Day, and with a pension much smaller than he had expected. He left London, and for a while taught French and Latin at a prep school in Leatherhead, returning full circle to the profession in which he had begun his adult life. He died in 1961 and is buried in Burley in the New Forest.

Was Denniston the right man to lead GC&CS during the war? Not if he was expected to be responsible for everything: administration was not his forte after all. But if the recommendations of the 1942 Army report, suggesting a new Deputy to take from Denniston all of the administrative burden, had been put in place, what might he have achieved? What is unquestionable is that he was treated badly, and was not recognised for the breadth and depth of what had been achieved between November 1919 and January 1942.

His memorial is that he built the UK's first unified cryptanalytic organisation, and developed the values and standards which made it a world leader. His work made GCHQ an organisation that partners aspired to emulate and work with. And it was his determination and innate belief in partnerships that ensured the Anglo-American cryptologic alliance was built and sustained. 

In 2011 his grave was rededicated, and GCHQ was represented alongside his family to honour its first Head.