The eldest son of Leslie Nailor and his wife Lily Matilda (née Jones), he was educated at Mercers' School and studied at Wadham College, Oxford, where he obtained his Bachelor of Arts degree in 1952 and his master of arts degree in 1955.

He then served as First Lord's representative on the Admiralty Interview Board, 1960–62; a member of the Polaris Executive, 1962–1967; and Assistant Secretary, Ministry of Defence, 1967-1969.

In his last posting, he dealt with future planning in Defence Secretariat 22, implementing the recommendations of Lord Fulton's Report.

While in this post he served additionally as Dean at the Royal Naval College, Greenwich, in 1982-84 and 1986–1988, as well as Chairman, British International Studies Association, 1983-1986.

He served as a member of the Political Science Committee of the Social Science Research Council, 1975–1981; the Foreign and Commonwealth Office advisory panel on arms control and disarmament, 1975–1988; and the Ministry of Defence advisory panel of historical records, 1979-1988.