Abstract: Cylinder locks for use in the locking of doors on opposite sides of a vehicle, each have a single barrel which carries tumblers that abut internal shoulders of the lock casing to obstruct turning of the barrel in an unlocking sense (different for the two locks) until the tumblers are withdrawn into the barrel by initial turning of an inserted key. The barrel in each case is free to turn in the opposite, locking, sense without any obstruction, turning in both senses being opposed resiliently by a coiled spring that embraces a spindle of the barrel externally of the casing. The tumblers of one lock are spaced by a bush forwardly within their barrel as compared with the tumblers of the other lock so that different sets of the cuts of the common key engage the tumblers of the two locks.