Oliver Miles was born on 6 March 1936, the son of George Miles and Olive (née Clapham). He was educated at Ampleforth College and Merton College, University of Oxford (taking Oriental Studies). In 1968 he married Julia, daughter of Professor J. S. Weiner; they have three sons and one daughter.
Miles entered the Diplomatic Service in 1960 and during his early postings served in Abu Dhabi [United Arab Emirates], Amman [Jordan], Aden [Adan, later South Yemen], Mukalla, Nicosia [Cyprus] and Jedda [Jiddah, Saudi Arabia]. His later positions included: Counsellor, Athens [Greece] (1977-80); Head of Near East and North Africa Department, Foreign and Commonwealth Office (1980-83); Ambassador to: Libya (1984); Luxembourg (1985-88); Under-Secretary on loan to Home Civil Service, Belfast [Northern Ireland] (1988-90); Assistant Under-Secretary of State (Economic), FCO (1990-91); Director General of Joint Directorate, Overseas Trade Services, FCO/Department of Trade and Industry (1991-93); Ambassador to Greece, 1993-96.