After joining the Treasury in 1979, Gus held various positions at the British Embassy in Washington, International Monetary Fund and the World Bank. From 2002 – 2005, he was Permanent Secretary at the Treasury and in 2005 became Cabinet Secretary on the retirement of Lord Turnbull. He held this position until 2011, serving three Prime Ministers. Gus studied Economics at the University of Warwick, and gained an MPhil in Economics from Nuffield College, Oxford and went on to lecture in economics at the University of Glasgow. Since October 2013 he has been non-Executive Chairman of Frontier (Europe). Gus was created a life peer in 2012, and sits in the House of Lords as a crossbencher. He became a Visiting Professor at the LSE in 2012.