Sir David studied at Oriel College, Oxford and at Johns Hopkins University. He joined the Foreign & Commonwealth Office in 1972 and served in Warsaw, New Delhi, Paris and Moscow. From 1995 to 1998 he was Ambassador to Israel and in 2001 he was the UK Permanent Representative at NATO (Brussels). He was Foreign Policy Adviser to the Prime Minister and Head of the Defence and Overseas Secretariat from 2001 to 2003. He was then Ambassador to the United States for four years from 2003 to 2007. Among other roles he currently acts as Senior Adviser to TRHs the Duke and Duchess of Cambridge and Prince Harry.