John Killick was born 18 November 1919, the son of Edward William James Killick and Doris Marjorie (née Stokes). He was educated at Latymer Upper School, then University College, London, (and became a Fellow of the college in 1973) and finally Bonn University [Germany]. In 1949 he married 1st, Lynette du Preez (née Leach) (died 1984), then 2nd, in 1985, I. M. H. Easton, OBE. He had no children.

After serving with the Suffolk Regiment, West Africa Force and Airborne Forces, (1939-46), Killick joined the diplomatic service. His career included: Foreign Office (1946-48); Control Commission and High Commission for Germany (in Berlin, Frankfurt and Bonn), (1948-51); Private Secretary to Parliamentary Under-Secretary, Foreign Office, (1951-54); British Embassy, Addis Ababa [Ethiopia], (1954-57); Canadian National Defence College, (1957-58); Western Department, Foreign Office, (1958-62); Imperial Defence College, (1962); Counsellor and Head of Chancery, British Embassy, Washington [United States], (1963-68); Assistant Under-Secretary of State, Foreign and Commonwealth Office, (1968-71); Ambassador to Soviet Union, (1971-73); Deputy Under-Secretary of State, FCO and Permanent Representative on Council of WEU, (1973-75); Ambassador and UK Permanent Representative to NATO, (1975-79).

Sir John Killick died in February 2004.