An S.E.5a pilot, William Roy Irwin joined the Royal Flying Corps in April 1917. In January 1918, he was posted to 56 Squadron where he was credited with his first victory in May. In August and September, he shot down eight Fokker D.VIIs in four days. Wounded in action on 15 September 1918, he was sent back to England. During World War II, Irwin served with the Royal Canadian Air Force and received the MBE in 1944.
Distinguished Flying Cross (DFC)
Lieut. (T./Capt.) William Roy Irwin.
This officer is a fine leader, displaying tactical skill and personal gallantry. On the 10th August he led his flight down to attack fifteen Fokkers. In the engagement that ensued he showed brilliant leadership and personal courage, accounting for two machines himself. He has destroyed five enemy aeroplanes and brought down three out of control.
Lieut. (A./Capt.) William Roy Irwin,
This officer is an exceptionally skilful pilot leader, combining fine fighting qualities with sound, clear judgement. On the 12 August  he led his patrol to attack a large formation of Fokker biplanes; he himself accounted for two of them. On a later date, attacking a formation of Fokker biplanes, he again destroyed two, the patrol accounting for two others.