He has been a Consultant Gastroenterologist and a lead mentor for university hospitals and has made a senior management contribution to the Research Excellence Framework (REF) 2014 as a clinical medicine (UoA1) lead. He has taken part in several studies including the isolation of label retaining cells (putative stem cells) in the oesophagus, identification of the genomic factors associated with the premalignant condition Barrett's oesophagus. He has studied the use of aspirin and proton pump inhibitors in one of the largest randomized clinical trials to prevent cancer. He is a highly cited clinical academic with a h-index of over 65. He has over 200 publications of which 150 are peer reviewed papers including in Gastroenterology, The Lancet, Lancet Oncology, Nature, Nature Genetics, Nature Communications, New England Journal of Medicine and Proceedings of the National Academy of Sciences USA.