The son of Fanny Leatry and her husband, Thomas Naish Blake, a brewer, Geoffrey Blake was born on 16 September 1882 at Bramley House, Alverstoke, Hampshire, England. He attended Winchester College before entering the Royal Navy at the age of 14. He attained the rank of lieutenant in October 1903 and later qualified in gunnery. On 6 February 1911 Blake married Jean St John Carr at the Church of the Oratory, Kensington, London; they were to have two daughters.
As gunnery commander of the Iron Duke, flagship of the Grand Fleet, Blake fought in the battle of Jutland in 1916. He later served as naval attaché in Washington DC (1919–21), director of the Royal Naval Staff College (1926–27), and chief of staff to the commander in chief, Atlantic Fleet (1927–29). In 1928 Blake was selected as commodore commanding the New Zealand Station and first naval member of the New Zealand Naval Board, his appointment dating from July 1929. He arrived on the Rotorua later that year accompanied by his wife; she had returned to England by November 1930.
Commodore Blake was to face a number of professional challenges during his term in New Zealand, each requiring all of his skill and acumen. The provision of aid to civil authorities is always difficult and Blake was called upon to undertake this on three occasions. In addition, his main responsibility – developing the operational capabilities of the force under his command – was complicated by reduced funding during the depression. As first naval member, Blake was an influential adviser to the New Zealand government at a time when its views differed widely from those of British authorities, particularly on naval strategy in the Pacific.
Blake's first challenge was to deal with a resurgence of the Mau troubles in Western Samoa in January 1930. He was ordered to take the Dunedin to Samoa and arrest leading members of the Mau movement. The ship raided various islands, making some arrests, but on the whole the operation was not a success.
When a devastating earthquake struck Hawke's Bay on 3 February 1931, Blake oversaw the embarkation of relief supplies and medical personnel on the Dunedin and Diomede, both of which sailed from Auckland later that day. Arriving at Napier the next morning, he took charge of the relief effort, helping to rescue survivors, clear debris, remove bodies, provide meals for the homeless, and patrol the streets to prevent looting. After a week civilian authorities resumed control. In addition to this work, Blake's men donated on average more than a day's pay each to the relief fund.
Civil authorities again sought the navy's assistance when serious rioting broke out in Auckland on the nights of 14 and 15 April 1932. Amid widespread vandalism and looting, Blake provided men from the Philomel and the Auckland division of the Royal Naval Volunteer Reserve to assist police in restoring order and patrolling the streets. A number of buildings, including the Magistrates' Court, the General Post Office and Auckland Harbour Board buildings, were guarded for several weeks afterwards.
At the same time, economic depression led to reductions in military expenditure and pay cuts for servicemen. Similar measures in Britain led to a mutiny of the Atlantic Fleet at Invergordon in 1931, but Blake was able to obtain significant concessions from the government and his efforts averted such a reaction in New Zealand.
During the 1920s and 1930s there was considerable international debate on naval disarmament. The London Naval Treaty of 1930 sought to limit the number and type of cruisers, and one of the key issues of that year's Imperial Conference was the construction of the Singapore naval base. These issues were of particular concern to New Zealand: cruisers were of vital importance in projecting British seapower throughout the Empire, and Singapore was the cornerstone of Britain's Pacific defence strategy. In both of these debates New Zealand took a singularly independent stand from Britain, although eventually acquiescing to the majority view in the interests of imperial harmony. As first naval member, Blake played a key role in providing the information and arguments on which the New Zealand government's position was based.
Blake was promoted to rear admiral in 1931 and returned to England the following year. He was appointed fourth sea lord and in 1936 became vice admiral commanding the Battle Cruiser Squadron and second in command of the Mediterranean Fleet. He retired due to poor health in 1938 but returned to the Admiralty in 1940. From 1942 to 1945 he was flag officer liaison to the United States Navy in Europe. From 1945 to 1949 he served as gentleman usher of the Black Rod in the British Parliament.
During his 40 years of service Geoffrey Blake received a number of honours: during the First World War he was made a DSO and a member of the Russian Order of St Anne; he was later appointed a CB (1929) and a KCB (1937). He maintained a keen interest in naval affairs until his death in London on 18 July 1968; his wife had predeceased him.