Fretwell was educated at
Chesterfield Grammar School, the
University of Lausanne and
King's College, Cambridge. He served in the
Royal Regiment of Artillery 1948–50 and joined the
Diplomatic Service in 1953. He served in Hong Kong,
Peking, Moscow and Washington, D.C., as Commercial Counsellor in Warsaw 1971–73, at the
Foreign and Commonwealth Office in London as Head of the European Integration Department 1973–76 and as Assistant
Under-Secretary 1976–79. He was
Minister in Washington, D.C. 1980–81,
British Ambassador to France 1982–87 and Political Director and Deputy to the
Permanent Under-Secretary of State for Foreign and Commonwealth Affairs 1987–90. After retiring from the Diplomatic Service, Fretwell was a member of the Council of
Lloyd's 1991–92, specialist adviser to the
House of Lords 1992–93 and specialist assessor for the
Higher Education Funding Council 1995–96. He was also chairman of the
Franco-British Society 1995–2005. Fretwell was appointed CMG in 1975, knighted KCMG in 1982, and promoted to GCMG in 1987. He died on 30 March 2017 at the age of 86. ==Personal life==