Dr McGrath was born in Liverpool in 1922. He was Medical Director of St John of God Hospital from January 1955 until December 1991 and Consultant Psychiatrist, St Laurence's (Richmond) Hospital (Beaumont Hospital from 1987), Dublin from 1956 until 1988. He was a Foundation Fellow of the Royal College of Psychiatrists and was a member of Council from 1974 to 1979, a member of the Court of Electors from 1979 to 1982 and Chairman of the Irish Division from 1974 to 1977. He was a member of Council and Censor of the Royal College of Physicians of Ireland from 1980 to 1982 and Chairman of the Section of Psychiatry of the Royal Academy of Medicine in Ireland from 1973 to 1975. He was President of the Medico-Legal Society of Ireland from 1966 to 1968 and has served on the Fitness to Practice Committee of the Medical Council of Ireland since 1989 and the Mental Health & Neurology Committee of the Medical Research Council of Ireland from 1969 to 1991.