Born in 1889 the eldest son of S W McCullagh of Belfast, he was educated at the Methodist College and Queen's University. On the outbreak of war he joined the RAMC and served throughout in France, winning the MC at the beginning and the DSO at the end of the war and being five times mentioned in dispatches; he was attached to 4 Field Ambulance, Guards Division till 1918 and then as Lieutenant-Colonel to 137 Field Ambulance, 40th Division. He held resident appointments at Queen Charlotte's and the Samaritan Hospital, where he became registrar, and then established himself in successful obstetric practice in London, serving on the staff of several hospitals and being a foundation Member of the College of Obstetricians and Gynaecologists. During the second world war he was ADMS to 47 London Division (TA) 1939 to 1942, and then ADMS in Sierra Leone 1942-44; in 1944-45 he was officer in command of Campbell College Military Hospital, Belfast. He was awarded the Arnott medal in 1956 by the Irish Medical Schools Graduates Association. McCullagh invented a number of special gynaecological instruments. He was a keen golfer, but was incapacitated towards the end of his life by fracturing his femur in a road accident. He practised at 138 Harley Street and lived at 7 Holly Lodge Gardens, West Hill, Highgate where he died on 17 August 1964 aged 75. He had married in 1932 Alison daughter of Henry Carrothers of Duneane, Ballynafeigh, Belfast, who survived him with their son and two daughters.