He was house surgeon to
Sir David Wilkie in the
Royal Infirmary of Edinburgh. After surgical posts at
Royal Leicester Infirmary he returned to Edinburgh as a demonstrator in anatomy and physiology. After obtaining the
FRCSEd in 1939, he was appointed surgeon to the Surgical Outpatient Department of the Royal Infirmary of Edinburgh. During
World War II he served as a Surgeon Lieutenant in the
Royal Naval Volunteer Reserve, based at the naval hospital in Bighi, Malta. In 1955 he was appointed as first occupant of the new James Stewart chair of surgery at
University of Melbourne. The chair which he took in Melbourne was based at the Alfred Hospital, then the
Royal Melbourne Hospital, with the establishment of
Monash University. He was also responsible for surgical teaching at St Vincent's Hospital and Prince Henry's Hospital. At the Royal Melbourne he established a renal transplant program under the direction of the nephrologists
Professor Priscilla Kincaid-Smith and Dr Vernon Marshall.
Peter Morris set up a tissue typing laboratory and a research laboratory in transplantation immunology in Ewing's department to support this service. Ewing's s other clinical interests were in head and neck cancer, parenteral nutrition and peripheral vascular disease. He also introduced the practice of using sheepskins under the patient to reduce the incidence of pressure sores. He was active in promoting
seatbelt legislation. The wearing of seatbelts in cars was made compulsory in the State of Victoria in 1970, a world first. He retired in 1977 and was appointed a
CBE in that year. Following retirement from the University of Melbourne, he spent six months in
Kuala Lumpur developing the academic surgical unit of the
University of Malaya. ==Personal life==