Locking mechanism 2 with a deadlock latch 4 in which a rotary cam 12 has means 12e to move the latch 4 between retracted and throw positions. The cam 12 is a modular arrangement with at least two inserting cams 12, 14, one of which 12 is driven by a panic release, the other of which 14 is driven by an actuator which is selectively locked by a deadlock. In one embodiment the latch 4 is provided with an anti-thrust mechanism 22, 28 to prevent the lock being forced into the retracted position whilst the cam also has means 12d to disengage the anti-thrust 22 prior to the cam 12 moving the latch 4.