Stevenston, Ayrshire born outside left Alec Thom began his football career playing with Leven Academy in 1910, Leven Amateurs in 1911, Vale of Leven in 1912, and Yoker Athletic in 1913, before joining Scottish League Dumbarton in 1913, making his debut that December against St Mirren. He scored 41 goals in 226 appearances over the next 7 years for The Sons and had loan spells with Kilmarnock in 1917, Ayr United and Motherwell in 1918 before joining Morton in 1920. He moved to Airdrieonians in 1921 and made the move south of the border to Second Division Hull City for £250 in September 1922.
He made his Football League debut against Fulham later the same month, and was a mainstay of The Tigers’ first eleven for the next four seasons, scoring 18 goals in 140 appearances before joining Swindon Town in the close season of 1926. He had a further four seasons at The County Ground, retiring in the summer of 1930 after having scored 25 goals in 112 appearances for The Robins.