Professor Kelly is a member of St John’s College and senior visiting fellow in the Primary Care Unit at the Institute of Public Health at the University of Cambridge.  He is a member of the Behaviour and Health Research Unit there which, among other things, carries out research about nudge theory and choice architecture. Between 2005 and 2014, when he retired, he was the director of the Centre for Public Health at the National Institute of Health and Care Excellence (NICE), where he oversaw all the guidelines relating to behaviour change, the prevention of the misuse of alcohol, tobacco control, the prevention of obesity and the promotion of physical activity. 

From 2005 to 2007, he directed the methodology work stream for the WHO Commission on the Social Determinants of Health.  He has published more than 250 papers, reports and chapters in medical, sociological, philosophical, business and public-health journals and books and is author/editor of seven books. In 2010, he was awarded the Alwyn Smith Prize of the Faculty of Public Health in recognition of his work on cardiovascular disease and alcohol misuse prevention. He is fellow of the Royal College of Physicians of Edinburgh and the Faculty of Public Health and Honorary Fellow of the Royal College of Physicians.