In December 1920, Gallacher was picked for the Scottish junior side to play agaist Ireland at Shawfield. Gallacher hit the Scotland equaliser with a fine header with two minutes remaining in the 1–1 draw. Among those at the game was James Jolly, secretary of Dumfries club Queen of the South. Jolly approached Gallacher after the game and offered him a trial at Queens, with the prospect of a £30 signing-on fee and £5 per week plus expenses should he do well in the trial. At the time Queens were in their second season after formation and, cup games aside, played only local fixtures. However it was professional football and that was good enough for Gallacher. Gallacher's name on the team sheet replaced Ian Dickson who was on his way to Aston Villa (they were two of the four players to play in Queens' first three seasons before moving on to successful careers in England's top division, the others being Dave Halliday and Willie Ferguson).