Allan was the son of George Colquhoun of Guildford and nephew of Mr and Mrs Andrew Colquhoun of Belmont Street, Loftus Park, New South Wales. He was a saddler, born in Glebe, New South Wales and was 18 years and 4 months when he joined the forces on 11 November 1915.
He served with the 13 Infantry Battalion, 15 Reinforcements in France and Belgium between 24 September 1916 and 11 April 1917 when he was declared missing in action. It was later found that he had been captured in Reincourt on 11 April 1917 and interned as a prisoner of war in Germany. On 2 June 1917 the Cumberland Argus and Fruitgrowers Advocate reported,
Private Allan Colquhoun aged 20 years, son of Mr Geo. Colquhoun of Guildford and nephew of Mr and Mrs Andrew Colquhoun of Belmont-street, Loftus Park. He is reported missing in France. He was in the cadets and was afterwards transferred to the citizen forces, shortly after which about two years ago he joined the Coo-ees as they passed through Parramatta. He was in camp at Liverpool and went thence to Egypt and England and has been in the firing-line about six months. He enjoyed the best of health in France.
On 1 December 1918 he was repatriated to England before returning to Australia on 5 March 1919.
Researched by Chrissie Crispin, Volunteer, Parramatta Heritage Centre, 2015