Abstract: A surface-mounted keylessly operated lock (10) comprises a chassis (11) mountable on one of two parts, especially a door and a door surround, to be locked and unlocked relative to one another and carrying locking means (17 to 23) transferrable between a locking state and an unlocking state respectively for the locking and unlocking, the locking means being electrically operable to cause or allow transfer from the locking state to the unlocking state. In addition, the lock includes a control module (16) mounted on the chassis (11) and carrying control means (30) for controlling supply of electrical operating power to the locking means. The chassis has a receptacle (25) for reception of an electrical energy source, especially batteries, for providing the operating power and the module (16) inclusive of the control means (20) is movable relative to the chassis (11) to permit access to the receptacle (25) to enable battery exchange without demounting of the installed lock.