Finlayson, a bald, mustached, squinting comedic actor, was born into the British upper class. He began acting in his teens. After appearing in several plays in Scotland, in 1915 or 1916 he got a part in a play touring the U.S.; he quit the troupe while it was in Los Angeles, hoping to work in films. Soon he was performing onscreen as one of the Keystone cops, and by the early '20s he was a regular player with Mack Sennett in feature-length comedies. He joined Hal Roach in 1923, playing leads and supporting parts in many comedies. A master of the double-take, he is best remembered as the top supporting player and foil in the films of Laurel and Hardy. He continued working onscreen during the sound era, but appeared in few films after 1942.