MB ChB Edinburgh 1925.
MacCallum was born on 25 August 1901 in Argyll. He was a general practitioner in Whalley Range, Manchester and was member of a number of medical boards. From 1935 to 1963 MacCallum was divisional surgeon to the St John's Ambulance Brigade and was also medical officer to the Northern Congregational College. During the war he served in the RAMC in the Middle East and Italy. MacCallum was a member of MMS and Manchester Medico-Ethical Association. His son Douglas Scott MacCallum also practiced medicine with his father.