Professor Sir Richard Doll

Millions of people are alive today who would otherwise be dead had Richard Doll not made his imperishable contribution to medical science. Nineteen-fifty marked the beginning of a defining decade for Doll. In that year, Doll and his great mentor, Austin Bradford Hill, published their iconic study into the causal link between tobacco and lung cancer. It was also at this point that Doll elected to make his career in medical statistics and epidemiology - the study of how nature, nurture, age and luck determine the risk of disease. Both events led him to become the leading cancer specialist of our time, contributing new concepts of people's relationship with the environment and opening up new fields for scientific study. In any social history of post-war Britain, Doll should have a central role.

Between the wars, there was an unprecedented rise in death from cancer of the lung; by the late 1940s, Britain had the highest lung cancer rates in the world, and the reasons for this were completely unknown. In 1950, for the first time, the number of deaths from lung cancer - 13,000 - exceeded those from tuberculosis. As the fear of infectious diseases began to recede, a new preoccupation with non-infectious diseases, such as cancer, heart attacks and strokes, began to engage medical researchers - though not yet society at large.

Tobacco is much the largest cause of premature death in developed countries, and Doll, himself a former smoker, did more than any other physician to identify its hazards. In 2001, he completed the 50-year follow-up of the famous study of smoking and mortality among 34,000 British doctors that he had started in 1951 (after publishing the 1950 study showing that smoking was "a factor, and an important factor" in the production of cancer).

The early results from his 50-year prospective study revealed for the first time the full range of diseases caused by smoking, and the later results first revealed the full hazards of lifelong smoking, and the benefits of quitting. It showed that half of all smokers were eventually killed by the habit, but, importantly, it also showed that stopping smoking works remarkably well. Tens of millions of deaths have potentially been avoided in the 20th century and maybe hundreds of millions this century by the recognition of the hazards of smoking and the benefits of stopping. Doll's contribution to global public health is so large that, according to the Nobel laureate Sir Paul Nurse, it "transcends the boundaries of professional medicine into the general community of mankind".

Through his own work and that arising from his discoveries and leadership - in collaboration with Hill, the father of medical statistics - he helped pioneer the randomised clinical trial. This objective evaluation of data, accurately measuring the effectiveness of medical procedures, is one of the major medical advances of the 20th century.

Having begun his career in research in 1946, Doll was still producing original work in his 93rd year. In all, he published over 500 scientific papers, and established a "Doll philosophy" based on rigorous scientific documentation. By his own admission it was "through a series of fortunate accidents" that he became an epidemiologist, but once the decision had been made, he became one of the truly great medical investigators of modern times.

William Richard Shaboe Doll was born in Hampton, Middlesex, in 1912. While he was attending Westminster School (at the same time as Kim Philby), the effect of reading exhaustively about the First World War, and the proselytising influence of Dick Sheppard, clergyman and influential pacifist thinker, made Doll become a pacifist. He was progressively radicalised by the General Strike, growing levels of unemployment, and the excitement of political activism, and his pacifism had been supplanted by socialism by the time he decided to sit for an open scholarship in mathematics at Caius College, Cambridge.

Because of his distinguished status at Westminster, Doll could have secured one of the "closed scholarships" the school had at Oxford and Cambridge, but this was anathema to him - he wanted to succeed in open competition. Serendipitously, Doll was driven to medicine by drink. He did all right on the first three days but on the third night some "friends" who had gone up the year before took him out to dinner at Trinity College, where he was treated to three pints of Trinity Audit Ale, 8 per cent alcohol, which was quite strong stuff. On the fourth day, his paper was not very good and the examiners could only offer him an exhibition. He was so annoyed with himself for that, he decided to take his father's advice and follow a career in medicine instead.

Doll entered St Thomas's Medical School in London in 1931. The young idealist soon recognised the effects of poverty on health when, as part of his medical training, he had to deliver 20 babies, half in people's homes. Lambeth then had some of the worst slums in London, and Doll became convinced that addressing social deprivation, the effects of malnutrition and living conditions was crucial to improving the nation's health.

With the emergence of Fascism, and the start of the Spanish Civil War, left-wing London medicine was in political ferment; in response Doll helped organise the St Thomas's Socialist Society, as part of London's Inter-Hospital Socialist Society. Its existence greatly antagonised the Dean, who declared that "there could be no such thing as a St Thomas's Socialist Society," as it would alienate the wealthy people whose contributions were essential for keeping the hospital at the time. While agreeing to make the existence of the society less visible to the hospital's benefactors, Doll stood up to the admonishment, saying, "Well, I'm sorry, but we have one."

The growing failure of capitalism pushed Doll further to the left - he described himself as a "democratic Communist" - and while still a student he walked part of the way with the Jarrow marchers in 1936, treating the bruised and blistered crusaders.

Recognising the need to fight Hitler, Doll joined the Royal Army Medical Corps Reserve in 1938. Within three days of war being declared, he was despatched to France as Medical Officer to the 1st Loyals, part of the British Expeditionary Force. After surviving the retreat to Dunkirk in 1940, he went on to serve in the Middle East in 1941-44. On the boat to Cairo, his friend Archie Cochrane remembered Doll arranging concert parties and organising the singing of "You'll get no promotion on this side of the ocean".

During 1944, Doll developed renal tuberculosis. His worst fears - that both kidneys were diseased - were not realised; only the left one had to be removed. Fully recovered by the spring of 1945, he started a year's post at St Thomas's Hospital, and once again entered into the political life of London medicine. He had met Joan Faulkner through the Inter-Hospitals Socialist Society before the war and on 8 May - VE Day - among the millions celebrating in the bright London sunshine were Richard and Joan. Their meeting on such an historic day marked the beginning of a lifelong love affair.

Doll now stood at a crossroads. Because of the Second World War, his initial hope of becoming at neurosurgeon was no longer possible, and his Communism had so antagonised Professor John McMichael at the Hammersmith that he was told, "You'll never work here." Fortunately, Doll was alerted to the possibility of a research post with Francis (later Sir Francis) Avery Jones, who was looking for a research assistant to help him in the study of the aetiology of peptic ulcer. It marked the beginning of a 20-year collaboration, and Doll continued clinical work at the Central Middlesex Hospital until he left London in 1969.

Doll's formative interests were "mathematics and public health medicine". So when, in 1947, Bradford Hill taught a brief course at the London School of Hygiene and Tropical Medicine in statistical ideas and methods Doll immediately enrolled. Doll's celebrated work on peptic and duodenal ulcers (later published as Occupational Factors in the Gastric and Duodenal Ulcers with an Estimate of their Incidence in the General Population, 1951) had greatly impressed Bradford Hill, and this led him to invite Doll to join his staff, to investigate the cause of lung cancer that was so alarming the Medical Research Council (MRC).

Politically, the men could not have been more different, but in their clarity of thought, intellectual integrity and scientific rigour they ushered in a new era in medicine: the intellectual ascendancy of medical statistics. Although their discovery of the hazards of smoking was originally met with apathy by the general public, and with a savage attack from R.A. Fisher (at the time the world's leading statistician), once doctors realised that smoking wasn't just killing their patients, but also killing them, a swing in the pendulum of perception was set in motion.

Doll immediately felt at home in the Statistical Unit at the London School of Hygiene and Tropical Medicine. In 1955 he carried out the first study into the carcinogenic effects of asbestos in Turner and Newall's factory in Rochdale. The results, which showed a tenfold increase of lung cancer in some or the workers, led the company to attempt to suppress the research. Showing indefatigable willpower and determination - both of which he had in abundance - Doll published the work, believing it to be scientifically valid.

In 1961 Doll succeeded Bradford Hill as the Director of the MRC's Statistical Unit. By then he had established an interest in radiation, which, like tobacco, would occupy him scientifically for the next half-century. In 1955, he researched the dangers from fall-out from testing H-bombs in the atmosphere. In radiation alone his contribution would have placed him at the top of epidemiology - his studies of ankylosing spondylitis and antenatal X-rays in hospitals in London and Edinburgh expanded our general understanding that the risk of cancer increased in direct proportion to radiation dose.

When talking to Doll, you did have the overwhelming impression that he was truly listening to what you were saying. Gentle, courteous and kind, he was friendly and always supporting of other scientists. One of the secrets of his success was his great ability to organise both his own time and other people's. He defined a programme of prevention, particularly in relation to cancer and cardiovascular disease and signposted the way forward for scientists, educationists and politicians.

For much of his life, he had two jobs and sometimes three at the same time. This was true when, to the surprise of many, he left London in 1969 to become the Regius Professor of Medicine at Oxford. In addition to enlarging the scope and prestige of his own research unit, he also transformed the Oxford Medical School into the one of the nation's leading research institutions.

Doll was an uxorious man - he and Joan were a dynamic and loving couple; and their years in Oxford were amongst the happiest. His retirement in 1979 was followed by one of the busiest and most productive periods of his life, during which he was responsible for establishing Green College, of which he became the first Warden. Over breakfast, he and Joan would study photographs of the college's students so they could greet them on first-name terms.

Joan died in 2001. After a long period, Richard Doll regained his formidable levels of concentration and his intellectual steam-engine once again began to fire on all cylinders. His integrity was his strongest weapon. In retirement he would willing appear in court cases if the cause was just. The solicitor Martyn Day, who opposed Doll on two occasions, saw at close quarters the impact of his testimony in court. "Doll was the most impressive expert witness I've ever seen," he said. "The effect was; 'If I'm saying it, it's almost certain to be true.' "

One of Doll's many legacies is the great vintage of people he trained in the Imperial Cancer Research Fund Cancer Studies Unit at the Radcliffe Infirmary, and who now, in both hemispheres, are making their own contributions to the health of the global community. Foremost among them is Sir Richard Peto, who was not only Doll's protégé, but an adopted member of the family.

Richard Doll was garlanded with honours; among these, he was elected to fellowship of the Royal Society in 1966, knighted in 1971 and made a Companion of Honour in 1996. He remained sentient and lucid to the end. He did once say to me, "What's the point in living if you're not working?" On a recent visit to Saudi Arabia he rode on a camel and, with that sense of humour that was never far away, he said, "I think the camel was more worried than me."

Conrad Keating