David George Irwin was born in Belfast on 1 February 1959 and educated at the Royal Belfast Academic Institution and Queen's University, Belfast. He qualified as a doctor and after his playing career ended he became medical officer for both Ulster and the IRFU. He played at centre for Queen's University and Instonians and was a mainstay of the Ulster provincial team. He led Ulster to victory over Australia in 1984 and Fiji in 1985 and also played against Romania in 1980, Australia in 1981 and New Zealand in 1989. In 25 internationals for Ireland between 1980 and 1990 he scored two tries and played for Scotland & Ireland against England & Wales in 1980. On the 1983 British Isles' tour of New Zealand David Irwin scored six tries in 11 appearances, including three tests.