This book tells the story of Alastair Denniston and the development of British signals intelligence from 1914 to 1945. Denniston was the first Operational Director of the Government Code and Cypher School (GC & CS), created in 1919. He had been a member of the Admiralty’s cryptographic branch known as Room 40 during WW1. In 1938, he recognised the need for academics and in particular mathematicians, to be involved in cryptographic work. He subsequently began planning for an expansion of GC&CS and drew up a list men who agreed in the event of war, to undertake secret work for the Foreign Office. When Britain declared war with Germany on 3 September, 1939, these men reported for duty at GC&CS’s new intelligence centre at Bletchley Park. In the early days of WW2, Denniston encouraged innovation and oversaw the early development of GC&CS, the forerunner of modern day GCHQ.  

He hosted the first meeting of significance between British and American signals intelligence representatives in his office at Bletchley Park in February 1941. His trips to the US and Canada in the latter part of 1941 played a significant role in establishing Anglo-American collaboration in signals intelligence and the ‘special relationship’ between the two countries. In February 1942, following a restructure of GC&CS, Denniston was given a smaller role overseeing diplomatic and commercial cryptanalysis work. His new department moved to offices in Berkeley Street in London where he remained in charge until the end of 1944. He was then encouraged to retire with a pension much smaller than he had expected. His death in 1961 was ignored by major newspapers and the British intelligence community.

Image: Cover of the Denniston biography.