Tyrrell, Sir William (1885–1968), RAF air vice-marshal, physician and rugby player, was born in Belfast on 20 November 1885, son of John Tyrrell of Belfast and Bangor, businessman, JP, and later alderman of Belfast, and Jennie Tyrrell (née Todd). His early education was at the Friends' School in Lisburn and the Royal Belfast Academical Institution, and he later entered QCB, where he studied medicine. He joined a special reserve unit of the Royal Army Medical Corps in 1912 and qualified as a doctor in 1913, graduating MB and B.Ch.; he was later awarded a DPH from QUB (1922). Throughout his college career, he played for the Queen's rugby club and was first selected to play on the Irish international team in 1910 in a match against France. He also played for Ireland in the 1912–13 and 1913–14 Five Nations championships and joined the British and Irish touring side, captained by Thomas Smyth (qv), that visited South Africa in 1912. Renowned for his skill as a forward, he was capped nine times and scored two tries for Ireland.
The outbreak of war in 1914 ended his international rugby career and he went on active service with the RAMC. He initially served as the medical officer of the 2nd Lancashire Fusiliers, and in 1915 was appointed to command the 1st Military Ambulance Corps. In 1916 he was appointed deputy assistant director of VIII Corps' medical services before taking command of 76th Field Ambulance (1917–18). A teaching posting followed at the RAMC school of instruction, and by the end of the war he had been promoted to lieutenant-colonel, awarded the MC (1914), the Belgian Croix de Guerre (1916), and a DSO and bar (1918), and mentioned in despatches six times.
He returned to Europe after the war and was seconded as principal medical officer to the Royal Air Force's HQ in Germany. In 1919 he took part in the expedition to Somaliland, and in 1920 he transferred to the RAF with the rank of squadron leader. He served as the senior RAF medical officer in Basra (1922–3) before serving as the principal medical officer in Palestine (1923–6). After a period of leave, he returned to England, where he took up a teaching appointment at the RAF college at Cranwell (1927–31). Further service in the Middle East followed and, promoted to group captain (1931), he served as the PMO in Iraq and the Middle East (1932–35), totally reorganising the RAF's medical services. In 1935 he was promoted to air commodore and returned to England, where he was attached to Training Command (1935–44). On the outbreak of the second world war, he was promoted to air vice-marshal (1939). During his service in the Middle East, he had gained a wide knowledge of tropical diseases and also the effects of dehydration and heat exhaustion. He drew on this knowledge in his lectures and also when designing medical training courses, enabling a new generation of RAF medical officers to operate more effectively when posted to the Middle Eastern theatre of operations. He was made a CBE (1942) and a KBE (1944). He retired from the RAF on age grounds in 1944. In 1945 he was appointed as the director of BOAC's medical services; he finally retired in 1947. QUB later awarded him an honorary LLD (1947) and he was made a knight of St John (1947).
Throughout his service career, he remained intensely interested in rugby. After his retirement he became active in the administration of the IRFU. In 1950 he was elected as the IRFU's president and enjoyed the satisfaction of seeing Ireland win the International Championship in 1951. He died on 29 April 1968.
He married (1929) Barbara Coleclough of Romsey, Hampshire; they had two sons and one daughter.