Major Greenwood was the foremost medical statistician of the first half of the 20th century in the UK. Trained in both medicine and statistics, his career extended over 45years during which he published eight books, 23 extensive reports and over 200 papers. His classical education extended to Latin and Greek, and he was fluent in German and French. We provide an overview of his life including family background, training and his career subdivided according to the places where he worked. We describe in particular the key role he played with others in the development of medical statistics within the Medical Research Council, the General Register Office, the Department of Health and the Universities. © 2015 The Authors. Statistics in Medicine Published by John Wiley & Sons Ltd.