William Patey was born 11 July 1953, the son of William Maurice Patey and Christina Kinnell Patey. He was educated at Trinity Academy, Edinburgh and the University of Dundee (MA Hons). In 1978, he married Vanessa Carol Morrell, having two sons.

Patey joined the Foreign and Commonwealth Office in 1975 and his diplomatic career included: MECAS, 1977–78; Commercial Attaché, Abu Dhabi [United Arab Emirates, UAE], 1978–81; Second Secretary, Tripoli [Libya], 1981–84; Near East and North Africa Department, FCO, 1984–85; Middle East Department, Iran/Iraq Desk, FCO, 1985-86; Permanent Under-Secretary's Department, FCO, 1986-88; First Secretary (Political), Canberra [Australia], 1988–92; Deputy Head, UN Department, FCO, 1992–94; Overseas Inspector, FCO, 1994–95; Deputy Head of Mission and Consul-General, Riyadh [Saudi Arabia], 1995–98; Special Adviser to Richard Butler, UNSCOM, 1998; Head, Middle East Department, FCO, 1999–2002; Ambassador to Sudan, 2002–05; Ambassador to Iraq, 2005–06; Director, Comprehensive Spending Review 2006-07; Ambassador to Saudi Arabia, 2007–10; Ambassador to Afghanistan, 2010–12.