Ronald George Clark was born in 1928 in Aberdeen. His parents were George and Gladys Clark and he was their second child. Educated at Aberdeen Academy, he left school at 16 with no plans for a future career and got a job as a laboratory technician at a local paper mill. This was to instil a lifelong interest in the quality of any paper item that he encountered. Unable to remain at the mill when jobs were reclaimed by returning army veterans, he moved to the Rowett Research Institute in Glasgow where his passion for biology developed. When called up for national service he joined the RAMC as a nurse and laboratory technician and, in 1950, qualified to study medicine at Aberdeen University. Graduating cum laude in 1956, he joined the staff of the Western Infirmary in Glasgow the following year and remained until 1960, when he took up a research fellowship at Harvard University and the Peter Bent Brigham Hospital in Boston. Fascinated by the work of John Kinney who was studying energy metabolism in surgical disease, then very much a new topic, he was to write that *this set the whole of my research programme for the rest of my career, while incidentally reflecting back to the work I did as a technician at the Rowlett*. Following 18 months in the USA he returned to Glasgow before moving to the Northern General Hospital in Sheffield in 1966 where, five years later, he was appointed professor of surgery. As a surgeon he was popular with his patients and took a great interest in the welfare of his staff and students. Inspired by his experience in the USA he spent the next 25 years developing the science of artificial nutritional support in the UK, which was to vastly improve the life chances of patients in intensive care units. As the country lacked a forum for the exchange of ideas on such a topic he established, and became the chair of, the UK surgical metabolic group which eventually became the clinical metabolic section of the nutrition society. Also a founder member of the European Society for Clinical Nutrition and metabolism, he was also its first executive chairman and founder editor of the journal *Clinical Nutrition*. He took on many administrative roles, including on NHS management committees, and also became pro-vice chancellor and dean of the medical school at Sheffield University. Renowned for being a person who got things done, during his tenure he oversaw the new law school, the refurbished physics block and (perhaps the one that gave him most personal satisfaction) the new football pitches. From 1982 to 1993 he was a member of the GMC and was on various committees covering contentious subjects such as the ethical dilemmas posed by AIDS and transplantation. During his early years in Glasgow he had met Tamar Harvie, a physiotherapist and, after they married, she accompanied him to Boston in 1960. When he retired they initially returned to Scotland where he continued to work as an examiner and remained an active member of the Moynihan Chirurgical Club. Eventually they moved back to England to be near their daughters where, having successfully recovered from lung and prostate cancer, he succumbed to ischaemic heart disease. He died on 7 November 2018 aged 90 and was survived by his wife, daughters Tamar and Deborah (a GP), and five grandchildren.