Derek Plumbly was born 15 May 1948, the son of John C. Plumbly and Jean Elizabeth (née Baker). He was educated at Brockenhurst Grammar School and Magdalen College, University of Oxford (taking a BA in PPE). In 1979, he married Nadia Gohar, having two sons and one daughter.

After teaching in Pakistan with the VSO, 1970-71, Plumbly joined the Foreign and Commonwealth Office, and his diplomatic career included the following posts: Third Secretary, FCO, 1972-73; MECAS, 1973-75; Second Secretary, Jedda, 1975-77; First Secretary, Cairo, 1977-80; FCO, 1980-84; First Secretary, Washington [United States], 1984-88; Deputy Head of Mission, Riyadh, 1988-92; Head of Chancery, UK Mission to United Nations, New York, 1992-96; International Drugs Co-ordinator, and Director, Drugs and International Crime, FCO, 1996-97; Director, Middle East and North Africa, FCO, 1997-2000; Ambassador to Saudi Arabia, 2000-03; Ambassador to Egypt, 2003-07; Chairman of the Assessment and Evaluation Commission, Comprehensive Peace Agreement, Sudan, 2008-11; Under Secretary General and Special Coordinator for Lebanon, United Nations, 2012-15.