Abstract: A locking device including a housing adapted for mounting in one part of an enclosure and defining an engagement surface means; a bolt retained by the housing and adapted for reciprocating movement therein between open and latched positions, the bolt comprising a latch portion adapted when in the latched position to engage another part of the enclosure movable relative to the one part thereof; and a key operated cylinder lock retained by and movable with the bolt during reciprocating movement thereof, the lock being rotatable between locked and unlocked positions. Also included is a locking member retained by and movable both reciprocally and rotationally with the lock and arranged to be engaged with the engagement surface means and prevent reciprocating movement of the bolt with the lock in its locked position; and to be disengaged from the engagement surface means to allow reciprocating movement of the bolt with the lock in its unlocked position.