Thomas was one of six children and the second son of Colin and Annabella McKenzie. His birth was registered at Inverell in 1884. He enlisted at Inverell in January 1916, stating he was a twenty seven year old Chaffcutter and that he had been apprenticed for 14 months to G.A. Baker, Saddler of Inverell. He was in fact over 31 when he enlisted.
With other district men he became one of the Second Contingent of The Kurrajongs who left Inverell together on 29th February 1916 and trained at Narrabri, Armidale and Rutherford camps. As a member of the 33rd Battalion he sailed from Australia on HMAT A30 Borda in October, arriving in England three months later. He was sent to France in March 1917 where he served until being killed in action on 21 July 1917. Thomas was buried at Bethlehem Farm West Cemetery, Messines, Belgium.
At Inverell Thomas has his name inscribed on the Honor Roll and Cenotaph and he was one of the 215 men for whom a memorial tree was planted in Kurrajong Parade in 1919. His name is also recorded on the Long Plain Honor Roll.