Irwin was an old boy of Sullivan Upper School and represented them at a Guild of Youth Rally in London during the King’s Coronation (1937). He was Captain of the School Rugby Football XV in 1937 / 1938 and in the same year he was awarded the School Cup for being the best all-round pupil.
On 4th April 1938 he joined Northern Bank at Head Office.
On 1st May 1939 he enlisted into the RAF Volunteer Reserve. Irwin was called up for Active Service on 22nd June 1940 with the rank of AC2. Promotion followed to Leading Aircraftman and Sergeant Pilot with Service Number 951459. He was serving with 57 Sqn Royal Air Force Volunteer Reserve.
Flying on an operation to Essen, Irwin was killed with 5 other crew on killed on 4th July 1941. A 6th member was injured when the Wellington IC R1589 Crashed at 00.08 hrs at Larman's Fen, Southerly Road, Feltwell, Norfolk. The cause of the crash - instrument failure.
Irwin is buried in Holywood Cemetery, Co. Down, Northern Ireland and is commemorated on the Glencraig War Memorial.
His brother, Flight Lieutenant William Thomas Irwin also saw service with the RAF (VR) and was killed in action on 3rd October 1943 aged 22. He was serving with 51 Squadron flying a Halifax II HR728 LX-D on an operation to Kassel when it crashed at Wietersheim - all 8 crew were killed.