Educated in Ireland and South Africa, Stacy joined the Royal Air Force in 1942 during World World War II and after pilot training in South Africa served as a fighter pilot in Burma with Number. 155 Squadron and then Number. 60 Squadron. After the war he served as a pilot with Number.
54 Squadron and then with Number.
72 Squadron. He was appointed Officer Commanding Number. 54 Squadron in 1956, Chief of the Nuclear Operations Branch at Headquarters Second Tactical Air Force in 1959 and Officer Commanding Number.
50 Squadron flying Vulcan B.1A bombers in 1963. He was made Deputy Director of Operations for Bombers & Reconnaissance in 1965 and then Station Commander first at Royal Air Force Coltishall and then at Royal Air Force Akrotiri in 1969.
46 Group in 1972, Assistant Chief of the Air Staff (Policy) in 1974 and Deputy Commander-in-Chief at Royal Air Force Strike Command in 1976.
Finally he became Commander-in-Chief, Royal Air Force Germany in 1977 and Deputy Commander-in-Chief at Allied Air Forces Central Europe before his death in 1981. He lived at Winchester in Hampshire.