MB BS Lond 1955, PhD 1962; FRCS Eng 1963.
Sewell was born in Bebington, Cheshire, on 9 January 1930, and studied medicine at King's College Hospital London where he was later lecturer in anatomy. Sewell was senior surgical registrar at Glasgow Royal Infirmary from 1966 to 1971 and was also made visitor of the Wellcome Surgical Research Institute in Glasgow. He was consultant surgeon to Ashton, Hyde and Glossop Hospitals, and was also Chairman of the Surgical Division and lecturer in the Nursing School. Sewell was a member of Manchester Medical Society, the Royal Society of Medicine and the Hunterian Society of London.