Removable plug lock

A removable plug lock including a plug which is rotatable by means of a correctly keyed operation key and rotatable and removable by means of a removal key, wherein said operation key operatively forces at least one plug restraining member to protrude from the surface of said plug and wherein said removal key operatively permits movement of at least one plug restraining member to a plug withdrawal position, comprising:

• a plug of substantially cylindrical configuration including, a keyway, and recesses adapted to locate a restraining member;
• a lock housing including, a cylindrical cavity for slideably receiving the plug, said lock housing having upon its internal surface a concentric groove being concentric to said longitudinal cavity and an internal longitudinal slot said longitudinal slot intersecting said concentric groove;
• a first restraining member substantially located within one of said recesses of said plug, said first restraining member being adapted to form a first protrusion, from the surface of said plug into said concentric groove, upon application of force to the first restraining member from within the keyway;
• a second protrusion from the surface of said plug which protrudes into said concentric groove,
• characterized in that, the lock is operable in a first mode by insertion of said operation key in the keyway to unlock said lock and apply force to said first restraining member thereby forcing said first restraining member to protrude from the surface of said plug into said concentric groove thereby preventing removal of said plug,
• further characterized in that, the lock is operable in a second mode by insertion of said removal key characterized by a configuration which unlocks said lock and permits entry of said first restraining member into said keyway, so that said plug may be rotated to align said second protrusion with said slot thereby allowing removal of said plug.