Mark Peakman trained in medicine at University College London and pursued postgraduate training in clinical immunology. After he received his PhD based on studies of the immune system in Type 1 diabetes he held a senior clinical research fellowship at the University of Pittsburgh. He subsequently returned to the UK and oversaw a research group at King’s College London in the Department of Immunobiology. The main focus of the research was the role of T lymphocytes in the aetiology of the autoimmune disease, Type 1 diabetes. In particular, the group has defined the critical targets for T cells that appear to have a role in the destruction of insulin-producing cells, and key immunological pathways through which this damage is mediated. This work led to the definition of targets enabling the design of a novel approach to therapy. This strategy, termed “peptide immunotherapy” was the first of its kind in diabetes and further phases of this programme are ongoing. In the future, a better understanding of the role of the immune response in Type 1 diabetes will promote the further development of these novel therapeutics into the clinical setting. Mark also had the role of designing and implementing mechanistic studies in the context of clinical trials of novel immunotherapies in type 1 diabetes.