Richard Doll was born to a prosperous family. He enjoyed telling the story of how, had it not been for drinking too much on the night before a major exam, he might have entered Trinity College, Cambridge to become a mathematician. But he failed the scholarship and decided to go into medicine instead. He graduated in 1937 from St. Thomas's Hospital Medical School in London. He spent some time on a voluntary research post under the professor of medicine at the Royal Postgraduate Medical School, Hammersmith that convinced him research was the field for him. During World War II, he served with the Royal Medical Corps in France and the Middle East. His diary as a battalion medical officer of the retreat to Dunkirk was published in the British Medical Journal in 1990. In 1944, he was discharged and got a research job at the Middlesex Hospital, studying occupational factors in the development of gastric and duodenal ulcers. He was launched on a path that would lead him to become one of the 20th century's foremost epidemiologists, seeking ways to unravel the connections between lifestyle, occupational exposure, and disease. He made headlines in 1950 when, with Sir Austin Bradford Hill, he made the pioneering finding that cigarette smoking was the number one cause of lung cancer. Doll's meticulous approach to the structure of research studies, to the mathematics they used and to the collection, analysis and quality of data needed to make them valid, won the respect of colleagues and scientists throughout the world. He did major work on the safety of the contraceptive pill and studied industrial causes of cancer, domestic dangers such as radon in houses, and the problems of low-level radiation exposure for the general population; however, the tobacco problem remained his main concern all life. In 1993, presenting the 40-year follow-up findings of the study of smoking and health, he spoke of the future effects of smoking in China, where millions of new smokers were taking up the habit. Long after his formal retirement, working jointly with Professor Richard Peto, his colleague over many years, Doll set up a major study to disentangle conflicting evidence about cholesterol levels and heart disease. He was elected a fellow of The Royal Society and in 1969, was named Regius Professor of Medicine at Oxford University. He was knighted in 1971.