It was at Sheffield that he made major contributions in training in public health medicine, not only in the university but nationally, for in 1977 he was appointed Academic Registrar of the Faculty of Community Medicine. In this post he was responsible for the development of training and examinations for the young faculty, enabling those wishing to make public health a career to achieve the high standards required for the specialty. He held this post until just before his retirement in 1984.
Knowelden was educated at Colfe's Grammar School in Lewisham, obtaining his medical training at St George's Hospital Medical School and qualifying in 1942. Called up to the Royal Naval Volunteer Reserve the same year, he served as a Surgeon Lieutenant in a Q-Class destroyer. His naval experience was later of great value when in 1977 he was appointed Civil Consultant in Community Medicine to the Royal Navy.
On demobilisation, he attended the Diploma in Public Health (DPH) course at the London School of Hygiene and Tropical Medicine. It was reported that he had achieved the highest ever marks in the intelligence test to which all DPH students at that time were subjected. He was then awarded a Rockefeller Fellowship in Preventive Medicine, enabling him to study in the United States, at Johns Hopkins School of Public Health, in Baltimore.
On returning to Britain, in 1949 he was appointed lecturer in the Department of Medical Statistics and Epidemiology and a member of the Medical Research Council's Statistical Research Unit at the London School of Hygiene under Professor Austin Bradford Hill. This relationship developed into a lifelong friendship and encouraged Knowelden to develop into one of the steadiest and most productive epidemiologists of his day.
As with his teaching, so it was with his research work; meticulous, careful, modest, but producing work widely recognised as of great importance. Much of his early work was concerned with the measurement of the efficacy of vaccination against whooping cough, of the efficacy of treatment of rheumatic fever, then of greater importance than it is today, and of the use of antibiotics in the treatment of pneumonia and other respiratory conditions.
A particularly important study, carried out in collaboration with Bradford Hill, showed a definite relationship between tonsillectomy and the later, often much later, onset of poliomyelitis. At about this time Knowelden also took a major part in the organisation of the trial of poliomyelitis vaccine. This involved the organisation of records on nearly two million children from all areas of Great Britain. He also developed an interest in the statistics of cancer and was instrumental in setting up cancer registries in Uganda and Jamaica.
In 1966, during his time at Sheffield, he established one of the first Medical Care Research Units funded by the Department of Health to investigate aspects of cost-effectiveness of service (rather than strictly clinical) aspects of innovation. His first study in this field was an investigation of the effectiveness and acceptability of early discharge after hernia repair. Another important study undertaken in Sheffield was a large study of sudden infant death syndrome (SIDS), which established the syndrome's various underlying factors more clearly.
He also played a major role as member or secretary of many Medical Research Council and Health Department committees, underlining his abilities as an organiser of great skill with enormous ability to elicit co- operation from the often numerous bodies and individuals involved in data collection.
After his retirement from full-time work in 1984, he became coordinator of academic training for Trent Regional Health Authority. Knowelden had been appointed a JP in 1962 and for many years served as a magistrate in Sheffield's Children's Court; he later assisted in hearing appeals from magistrates' courts in the area. He was also an accomplished musician and was a great lover of chamber music and opera.
I first met John Knowelden in 1953 when I was a student at the London School of Hygiene and Tropical Medicine where he taught practical medical statistics to DPH students. His teaching was typical of the man: no fireworks, no flashes of brilliant oratory, no sarcasm for non- statistically minded students, but meticulous attention to detail, great patience, and a friendly and helpful approach to all whom he taught. His brilliance was usually understated by his modesty, and his gentle approach to those who sought his advice.
He faced his final illness with great courage. It was typical of him that shortly before his death, and in great pain, he visited my family in Scotland. Having a pre-dinner drink we felt that "good health" was an inappropriate toast. Without hesitation, Knowelden suggested "survival".
John Knowelden, epidemiologist: born London 15 April 1919; Lecturer in Medical Statistics and Member, Medical Resesarch Council Statistical Research Unit 1949-60; Editor, British Journal of Preventive and Social Medicine 1959-69, 1973-76; Professor of Community Medicine (formerly of Preventive Medicine and Public Health), Sheffield University 1960-84, Academic Registrar, Faculty of Community Medicine 1977-83; Civil Consultant in Community Medicine to the Royal Navy 1977-84; CBE 1983; married 1946 Mary Sweet (two sons); died Scarborough 23 July 1997.