Allan Adams was born at Brisbane, Queensland. He moved with his family to the NSW far North Coast as an adolescent. The Adams family lived in a village by the name of Possum Creek in the Byron Bay hinterland.
He enlisted with the 41st Battalion at Lismore in 1916 and saw action on the Western Front. He was posted to the War Graves detachment at the end of hostilities.
Allan returned to Australia in 1919, and in 1920 his rugby league career took off. He was first noticed in 1920 in a match between a Byron Bay representative team and a visiting Newtown side from Sydney. Allan was playing on the wing and noted for his size and speed. At that time he was playing for the local Bangalow Royals Rugby League team.