<p>A lock comprises a shield in the form of a cover (1) which extends over the mechanism of the lock and a staple (7) engaged by the lock, preventing access to the mechanism of the lock and to the staple by tools such as bolt cutters. The lock is preferably electronically operated containing electronic circuitry therein and the cover provides a protective housing for the circuitry, battery and an antenna (6) associated with the circuitry.</p>
