While enjoying a holiday in Dumfries, Gallacher took ill with double pneumonia. Doctors believed that he would never play football again, but a week later he was said to be recovering well. While in Dumfries Infirmary he was approached by directors of Airdrieonians who had noted his performance in a recent challenge game. At this time if a player was not playing league football at any time then he was free to sign for whoever offered a contract. Airdrie offered a contract and Gallacher signed without a second thought. In his nine games for Queens Gallacher hit 19 goals, with the game against Hawick on 13 April 1921 being his last. He however returned to Palmerston Park many times to play in and referee charity matches. Gallacher was also among the jubilant crowd who watched Queens win in their 1929–30 season-ending 2–1 Charity Cup final win against Mid-Annandale.