Avery Jones was educated at the Sir John Leman School, Beccles, and at St Bartholomew's Hospital Medical School. He qualified in medicine in 1934 and was successively house physician to Professors Sir Francis Fraser, Leslie Witts and Ronald Christie, three of the most distinguished physicians of the time.
In 1936, he obtained a Baly Research Scholarship and was appointed assistant to the professorial medical unit under Witts, where he was introduced to the revolutionary technique, pioneered in Denmark, of liberal feeding for patients with bleeding peptic ulcers, instead of sedation and starvation, and he showed that the fatality of the condition could be dramatically reduced by drip blood transfusion and adequate amounts of water and salts by mouth.
In 1937 he attended (as a guest) the foundation meeting of a gastroenterological club (later to become the British Society of Gastroenterology) which had been organised by Sir Arthur Hirst, fell under his spell, and became committed to gastroenterology for life.
In 1940, Avery Jones was appointed to the staff of the Central Middlesex Hospital, as a physician with a special interest in gastroenterology, where he joined a group of specialists whose joint work was to establish the hospital as a centre of excellence that rivalled the university hospitals in central London. Collaboration, rather than competition, characterised the work: before long Avery Jones had amassed a personal experience of the natural history and prognosis of peptic ulceration that was unique and which he built on by persuading his surgical colleagues to operate on patients directly from his wards, leaving their post-operative care to him; something that was only just beginning to be managed scientifically with detailed attention to biochemical control.
The massive experience that he gained in this way of the results of different methods of treatment of gastric and duodenal haemorrhage enabled him to lay out a practical programme for managing one of the most complex medical emergencies; this resulted in a progressive and sustained reduction in the fatality of the condition.
Among his many other special interests were the development of gastroscopy, which he was among the first to use routinely when the flexible Wolf-Schindler gastroscope became available, and the use of randomised controlled trials, which, with help from me, he was the first to use to assess the value of the myriad treatments that were recommended for gastric and duodenal ulcers. I had joined his group in 1946 with the support of a Medical Research Council grant to study their occupational causes. Our co-operation over more than 20 years established, inter alia, that the bland diets then routinely prescribed for therapy were not beneficial, but that the advice to stop smoking was.
Avery Jones was a superb diagnostician and unremitting in his attention to his patients' needs, visiting his wards routinely at 10 o'clock at night to monitor the progress of those who were seriously ill. His clinical skills were recognised by an appointment as consultant gastroenterologist to St Mark's Hospital for diseases of the large bowel, and to the Royal Navy.
Not satisfied with giving his patients the best possible medical care within his power, he sought to ensure that the structure of the National Health Service played its part equally effectively. He was a member, and later the Chairman, of the King's Fund Committee on Catering and Diet in hospitals. He chaired the King Edward VII Hospital Fund Development and Emergency Bed Service Committee, and the Department of Health and Social Security's Advisory Committee on Medical Records.
In his later years he developed a particular interest in nutrition, chaired the Royal College of Physicians' Working Party on Dietary Fibre, was a member of the scientific committee of the British Nutrition Foundation, and the first chairman of the Royal Society of Medicine's Forum on Food and Health.
Internationally his work was recognised by the invitation to give the first Memorial Lecture of the American Gastroenterological Association, election as an honorary fellow of the American College of Physicians, and the award of the first Henry Bockus Medal of the World Organisation of Gastroenterology. At home he was invited to give the Goulstonian lecture at the Royal College of Physicians, awarded to the youngest new fellow of the college, and later the Harveian Oration, its most prestigious senior award, and, an extreme rarity for a physician, was made an honorary Fellow of the Royal College of Surgeons.
Avery Jones (always just "Avery" to his friends and colleagues) was the antithesis of the television picture of a senior medical consultant; he was quiet, unassertive, attentive to everything a patient had to tell him, but nevertheless radiated confidence and left everyone feeling better for his visit. He was never rushed or flurried (even if sometimes inevitably late) and worked a 16-hour day. After I had known him for some years I asked him if he ever took a holiday. "Of course," he said. "I had one last year." On further enquiry it turned out to have been on Sunday 26 July.
Francis Avery Jones, physician and gasteroenterologist: born Briton Ferry, Carmarthenshire 31 May 1910; physician, Central Middlesex Hospital 1940-74; consultant, St Mark's Hospital 1948-78; consultant, Royal Navy 1950-78; Editor, Gut 1965-70; CBE 1966; Kt 1970; President, Medical Society of London 1977-78; President, Medical Artists Association 1980-91; President, British Digestive Foundation 1981-92; married 1934 Dorothea Pfirter (died 1983; one son), 1983 Joan Edmunds; died Chichester, West Sussex 30 April 1998.