A small proportion of the documents relate to Gretton's naval career between 1926 and 1963, and include reports, standing orders, workbooks and journals. The majority of the archive, however, relates to Gretton's life after active service, including: his correspondence with naval personal, fellow academics and political figures; projects and research on a variety of naval defence topics, including the 1966 Defence White Paper, and work for the Ditchley Foundation and the Institute of Strategic Studies; typescripts and preparatory material for speeches, lectures, book reviews and contributions to radio and television programmes presented by Gretton; and research and copies of articles for newspapers and leading publications, including the Naval Review and the Dictionary of National Biography. All of Gretton's published books (see above Biography) and unpublished works are extensively represented by correspondence, notes, research materials and full drafts, in the case of 'The Forgotten Factor' (on the Spanish Civil War), 'The Battle of the Atlantic', 'The True Glory' (on minor naval actions in World War II) and 'The Victorian Navy'. The collection also includes a small number of personal papers, including an outline of Gretton's working life, October 1942-July 1969, written by his wife, and a bound volume of memoirs, written by Gretton himself.

Administrative / biographical background
Gretton joined the Royal Navy as a cadet at Dartmouth Naval College in 1926. His early service career included acting as a Midshipman on the battle cruiser RENOWN in the Mediterranean, 1930, as Sub-Lieutenant in the Royal Yacht VICTORIA AND ALBERT, summer 1934, in the aircraft carrier COURAGEOUS, and then in the cruiser DURBAN during the Abyssinian crisis and the Spanish Civil War. During the 1936 Arab Rebellion in Palestine, Gretton assisted the Army in protecting truck convoys and later aided police to contol the souk in Haifa, for which he was awarded the DSC. He was subsequently appointed Seamanship & Sports Officer at the boys' training establishment, HMS IMPREGNABLE, at Devonport, and then spent two years as a House Officer at Dartmouth. During Easter 1939, Gretton undertook an anti-submarine course at the Portland A/S HMS OSPREY, which was to have a profound effect on his later life. At the beginning of World War II, Gretton was appointed 1st Lieutenant of the destroyer VEGA, escorting East Coast convoys. During the Norwegian campaign of 1940, he served as 1st Lieutenant of the destroyer COSSACK, which participated in the second battle of Narvick on 13 April. His first command was the destroyer SABRE, in which he escorted Atlantic convoys. After his promotion to Lieutenant-Commander in 1942, Gretton took command of the destroyer WOLVERINE. The ship rammed and sank the Italian U-boat DAGABUR during the PEDESTAL Convoy to Malta in August, for which Gretton was awarded the DSO. In December 1942, he was appointed to lead B7 Escort group in the destroyer DUNCAN, and in April 1943 they were involved in the battle surrounding Convoy ONS5. The actions of B7 led to extensive U-boat losses, forcing Admiral Doenitz to withdraw from the North Atlantic. In recognition, Gretton was awarded the first Bar to his DSO. After U-boats returned to the North Atlantic in the summer of 1943, Gretton's further actions led him to attain a second Bar to his DSO. From 1944-1946 Gretton served in the Admiralty Plans Division, he was promoted to Captain in 1948 and in the early 1950s he acted as Naval Assistant to the First Sea Lord, commanding the cruiser GAMBIA. He then became Chief of Staff to Admiral, the Joint Services Mission, Washington. From 1956-1957 he was Commodore in command of the Naval task group for 'Operation Grapple', the British atomic bomb tests at Christmas Island. In 1958 he was promoted to Rear-Admiral, served as Senior Naval Member of Directing Staff of Imperial Defence College, 1958-1960, and was Flag Officer, Sea Training, from 1960-1961. As Vice-Admiral, he acted as Deputy Chief of Naval Staff and Fifth Sea Lord from 1962-1963. He retired through ill-health in 1963. He subsequently became Domestic Bursar (1965-1971) and then Senior Research Fellow (1971-1979) of University College, Oxford. Gretton also acted as the Vice-President of the Royal Humane Society (Testimonial, 1940). He was awarded the OBE in 1941, CB in 1960 and KCB in 1963. His published works include: 'Convoy Escort Commander' (1964); 'Maritime Strategy' (1965); 'Former Naval Person - Churchill & the Navy' (1968); and 'Crisis Convoy - The Story of HX231' (1974).