Born on 24 January 1868 at 22 Henry Street, Cork, eldest of the three sons of Patrick O'Hea and Juliet Lawes Woodforde, his wife. His father was a superintending inspector of HM Inland Revenue at Somerset House, London. His grandfather was W T G Woodforde, MD, of Bow, and his great-grandfather Henry Clutterbuck, MD, three times president of the Medical Society of London. He was educated at Lewes, and at St George's Roman Catholic College, which was then at Croydon but later moved to Weybridge. He began his medical training at St George's Hospital, but completed it at St Bartholomew's. He served as house surgeon at the London Temperance Hospital, as house surgeon and registrar at the Royal Eye Hospital, and as clinical assistant at St Bartholomew's. O'Hea practised for many years at Catford, London, SE, and served as medical officer to the Post Office, the Board of Education, and the London County Council Schools. He wrote a handbook on the care of children. He was commissioned captain, RAMC, in 1916, and served in hospital ships, at Gallipoli, and in prisoner of war camps. After the war he was for a time a ship's surgeon in the White Star line on the American and Australian routes. He then returned to practice in south-east London, and was a consulting neurologist to the Ministry of Pensions. When war broke out again in 1939, though over seventy O'Hea joined the Ellerman line as a ship's surgeon and saw active service in the Mediterranean and elsewhere. He continued to serve the company after the war and made his last trip to India when nearly eighty. O'Hea married on 22 August 1915 Marion Gertrude, daughter of Thomas Henry Burke; there were no children. He died at 106 Park Lane, Croydon on 17 April 1950, aged 82, and was buried at Queen's Road cemetery, after a requiem mass at St Mary's Roman Catholic Church, Wellesley Road, Croydon. He was a most charitable man, and though shy was always popular especially as a ship-mate.