John's recent work has focused on making medical education more professional, ensuring high-quality student clinical placements, supporting junior medical staff training, and forging partnerships with NHS colleagues. His earlier research was in respiratory disease, including studies into the prevalence of asthma and chronic bronchitis in Africa - he was one of the first to demonstrate the comparative rarity of asthma in African children. He began his consultant career in the NHS in Leicester where he introduced the use of fibre optic bronchoscopy. As well as Zimbabwe, he has worked in Japan and Ethiopia on assessing medical education.