Manley Power was born 10 January 1904, the son of Admiral Sir Laurence E. Power, KCB, CVO. He was educated at the Royal Naval Colleges at Osborne [Isle of Wight] and Dartmouth [Devon], and in 1930 married Barbara Alice Mary Topham; they had one daughter (and one son deceased).

Power joined the Navy as a Cadet in 1917, and in the early part of his career, served mainly in submarines, as: Midshipman (1921); Sub-Lieutenant (1924); Lieutenant (1926); Lieutenant-Commander (1934). In 1939 he was promoted to Commander and appointed as Staff Officer (Operations) to the Commander-in-Chief, Mediterranean, Vice-Admiral Sir Andrew Cunningham. In 1942 he was given command of HMS Opportune, escorting Russian convoys, before returning as Staff Officer (Operations) in the Mediterranean in September 1942, for the invasion of North Africa. Following the invasion, Power rejoined the staff of Commander-in-Chief, Mediterranean, as Staff Officer (Plans), helping to plan the invasion of Sicily. He was promoted to Captain in 1943, and Deputy Chief of Staff (Plans), and stayed in the Mediterranean until March 1944, planning the invasion of Italy and the Anzio landings. Power then became captain of the 26th Destroyer Flotilla, taking part in the Normandy landings [France], and as captain of the destroyer HMS Myngs took part in an action to destroy an enemy convoy off the Norwegian coast in November 1944. He was then appointed to command HMS Saumarez in the Eastern Fleet, and his flotilla destroyed the Japanese cruiser Haguro in May 1945. Following the war, Power served as Deputy Director of Plans in the Admiralty between January and July 1946, then as Senior Naval Member of the Directing Staff at the Joint Services Staff College, later becoming commander of the Portland [Dorset] naval base. Following this he served as Flag Captain to the Commander-in-Chief, Home Fleet [Admiral Sir Philip Vian], then in May 1952 as Chief of Staff to the Commander-in-Chief Mediterranean [Admiral 1st Lord Mountbatten]. He was promoted to Rear-Admiral in 1953, and in the following year was appointed Senior Naval Member of the Directing Staff of the Imperial Defence College. Power was then Flag Officer Aircraft Carriers between 1956 and 1957 (becoming a Vice-Admiral in 1956), and Deputy Chief of Naval Staff, and Fifth Sea Lord, from 1957 to 1959. He was made an Admiral in 1960, and Power's final appointments were as Commander-in-Chief, Portsmouth [Hampshire] and Allied Commander-in-Chief, Channel (1959-61), until his retirement in 1961.

Power's honours and awards include: KCB 1958 (CB 1955); CBE 1943 (OBE 1940); DSO 1944, Bar 1945; DL. He died in May 1981.