Mariot Leslie was born in Edinburgh [Scotland] on 25 June 1954, daughter of Stewart Forson Sanderson and Alison Mary Sanderson. She was educated at George Watson’s Ladies’ College, Edinburgh, Leeds Girls’ High School and then St Hilda’s College, University of Oxford (BA 1975). In 1978 she married Andrew David Leslie, having two daughters.

After a brief spell in the Scottish Office from 1975, Leslie joined HM Diplomatic Service in 1977 and during her diplomatic career served in the following posts: Singapore, 1978-81; Bonn [Germany], 1982-86; Paris [France] (on secondment to Quai d’Orsay), 1990-92; Head, Environment, Science and Energy Department, Foreign and Commonwealth Office, 1992-93; Scottish Office Industry Department, 1993-95; Head, Policy Planning Staff, FCO, 1996-98; Minister and Deputy Head of Mission, Rome [Italy], 1998-2001; Ambassador to Norway, 2002-06; Director, Defence and Strategic Threats, 2006-07, Director General, Defence and Intelligence, 2007-10, FCO; Member, Joint Intelligence Committee, 2007-10; UK Permanent Representative, UK Delegation to NATO, 2010-14.