John Fretwell was born 15 June 1930, the son of the late Francis Thomas Fretwell and of Dorothy Fretwell; he married 1959, Mary Ellen Eugenie Dubois. Fretwell was educated at Chesterfield Grammar School, Lausanne University and King’s College, Cambridge (MA).

After serving in the forces, 1948-50, Fretwell joined the Diplomatic Service in 1953. His postings included: 3rd Secretary, Hong Kong, 1954-55; 2nd Secretary, Peking [China], 1955-57; FO, 1957-59; 1st Secretary, Moscow [Soviet Union], 1959-62; FO, 1962-67; 1st Secretary (Commercial), Washington [United States], 1967-70; Commercial Counsellor, Warsaw [Poland], 1971-73; Head of European Integration Department (Internal), FCO, 1973-76; Assistant Under-Secretary of State, FCO, 1976-79; Minister, Washington, 1980-81; Ambassador to France, 1982-87. He served as Political Director and Deputy to the Permanent Under-Secretary of State, Foreign and Commonwealth Office, 1987-90, and was a Specialist Adviser, House of Lords, 1992-93.

Sir John was awarded the GCMG 1987 (KCMG 1982; CMG 1975). He died on 30 March 2017.