Michael Arthur was born 28 August 1950, the son of John Richard Arthur and of Mary Deirdre (née Chaundy). He was educated at Watford Grammar School, Rugby School and Balliol College, University of Oxford. In 1974 he married Plaxy Gillian Beatrice (née Corke), having two sons and two daughters.

Arthur entered the Diplomatic Service in 1972, and his diplomatic career included: UK Mission to United Nations, New York, 1972; Foreign and Commonwealth Office, 1973-74; 3rd, later 2nd Secretary, UK Permanent Representation to EU, 1974–76; 2nd Secretary, Kinshasa [Zaire, later Democratic Republic of the Congo], 1976–78; European Community Department (Internal), FCO, 1978–81; Private Secretary to Lord Privy Seal, 1981; Private Secretary to Minister of State, FCO, 1982; 1st Secretary, Bonn [Germany], 1984–88; Head, EC Department (Internal), FCO, 1988–93; Senior Associate Member, St Antony’s College, University of Oxford, 1993; Counsellor and Head of Chancery, Paris, 1993–97; Director (Resources) and Chief Inspector, FCO, 1997–99; Minister and Deputy Head of Mission, Washington [United States], 1999–2000; Economic Director, then Director-General, EU and Economic, FCO, 2001–03; High Commissioner, India, 2003–07; Ambassador to Germany, 2007–10.