David took a double first in Natural Sciences (Physiology) at Cambridge before serving in the Royal Engineers. After retraining in medicine, including a PhD in exercise metabolism, in Oxford, he completed his training as a cardiologist and general physician. He works in Oxford as the clinical lead for exercise investigation and cardiopulmonary exercise testing. His main clinical interest is the investigation of unexplained exertional symptoms. He has a Diploma in Aviation Medicine and maintains a research interest in environmental medicine (hypoxia). He has recently handed over as clinical lead for the UK Defence Aviation Medicine Service. During the recent pandemic he developed and leads the physicians’ service for post-COVID illness in Defence, the Defence COVID-19 Recovery Service. He is a lecturer in military medicine in the Academic Department of Military Medicine and a lecturer in clinical medicine at St Hugh’s College, University of Oxford.