Gavin was University Reader in Macroeconomics at Oxford University and Official Fellow and Tutor at Lady Margaret Hall.

He was also a co-editor of the Oxford Bulletin of Economics and Statistics, an associate member of Nuffield College, an associate consultant for OXERA, an editorial board member of the Oxford Review of Economic Policy, and an editorial fellow of Oxonomics. He was a special advisor to the House of Commons Select Committee on Trade & Industry.

He was a tutor on the Oxford University Business Economics Programme (OUBEP), and he also taught the macroeconomics elective on the Masters in Financial Econometrics at the Said Business School.

Until October 2000 he was a Research Fellow and Research Officer at Nuffield College, Oxford, working on an ESRC project with David Hendry, John Muellbauer, and Jurgen Doornik. He was also been a stipendiary lecturer at Oriel, St Hilda's and St Catherine's Colleges, and did my doctorate at Nuffield College. Between 1990 and 1992, he was an Economic Assistant at the Department of Trade and Industry, and before that he did a Masters' at Bristol University, his undergrad at Lancaster University, and went to school at Merchant Taylors' in Northwood.