MB ChB Aberdeen 1923.
Catto was house surgeon at Oldham Royal Infirmary before being appointed medical officer for Hulme Dispensary, Manchester. He later practised in Withington and Didsbury. Catto was a member of Manchester Obstetrical Society and was chairman of the Manchester Division of the British Medical Association from 1959-1962. Catto was first provost of the Northwest Faculty of the College of General Practitioners and an active member of the General Medical Services Committee.