Abstract: A barrel lock padlock is provided which can be used to engage the hasp-and-staple fitted to an enclosure such as a gas or electricity meter box. The housing of the barrel lock has a slot into which the staple can be passed to align with the bore in the housing in which the plunger of the barrel lock is movable, so that when the plunger is moved to the locking position by its spring it passes through the staple to lock the box. A key is passed through a key hole in a cap of the lock to engage the plunger and retract it, allowing the padlock to be removed from the staple.