Once a Jolly Swagman (U.S. title: Maniacs on Wheels) is a 1949 British film starring Dirk Bogarde, Bonar Colleano, Bill Owen, Thora Hird and Sid James.

[1][2] It was written by William Rose and Jack Lee, based on the 1944 novel of the same title by Montagu Slater.

Director Jack Lee later said he enjoyed making the film "because it was physical, there was action and I had good actors.

Bonar Colleano as Tommy provides comedy relief in his inimitable American way, and Bill Owen and Renee Asherson as Lag and Pat head a competent supporting cast.

Many scenes are superfluous, and part of the plot irrelevant, but the film is original and entertaining, presenting the "back stage" side of track life with realism and sincerity.