The collection includes Denning's certificates and commissions, 1918-1958; letters of appreciation for his services, 1933-1960; correspondence relating to books on naval intelligence and his work as secretary of the Services, Press and Broadcasting Committee, 1963-1979; and personal letters relating to his awards and retirement, 1945-1965. Also included are Denning's lectures and lecture notes, 1937-1957; official reports from the Second World War; essays on the Operational Intelligence Centre written by Patrick Beesly; a series of Admiralty aerial photographs, 1941-1945; and various newspaper articles and magazines.

Administrative / biographical background
Denning was born at Whitchurch, Hampshire, in 1904. After attending Andover Grammar School, he joined the Royal Navy as a special entry cadet in 1921. His eyesight was not good enough for a career as an executive officer, but he excelled in the paymaster branch and was quickly rewarded by several appointments as secretary to senior executive officers. With the rank of paymaster lieutenant-commander Denning joined the Naval Intelligence Division in 1937 and began to organise the Operational Intelligence Centre (OIC). This maintained large-scale plots of positions and movements of vessels derived from every form of intelligence, including decrypts produced by the Government Code and Cypher School. During the Second World War, the OIC was the centre of intelligence for the conduct of naval campaigns and Denning was responsible for overseeing the plot on which movements of enemy surface ships were recorded. He also acted as chief advisor to the first lord and first sea lord on operations necessary to protect Allied shipping and to intercept enemy forces. Denning was promoted to the rank of paymaster commander in 1941, paymaster captain in 1951, and rear-admiral on the general list in 1958. After the Second World War, he was appointed Director of Administrative Planning at the Admiralty, and in 1956 he became director of the Royal Naval College, Greenwich. In 1958 he was appointed Deputy Chief of Naval Personnel and in the following year Director of Manpower at the Admiralty. Denning was selected to be Director of Naval Intelligence in 1960, the first non-executive officer to fill that post. From 1964 to 1965 he acted as Deputy Chief of the Defence Staff. He was appointed OBE in 1945, CB in 1961, and KBE in 1963. After retiring in 1967, he became secretary of the Services, Press and Broadcasting Committee at the Ministry of Defence (the 'D Notice Committee'). He died at Micheldever, Hampshire, in 1979.