Abstract: A locking mechanism is provided for locking and unlocking a vehicle door latch mechanism. The locking mechanism includes a housing (17) for securing to the vehicle, a barrel (1) rotatable within the housing, a drive (7, 37) selectively engageable between the barrel and the door latch mechanism and means (23) to disengage the drive, wherein the barrel (1) has an unlocked and a locked mode such that rotational movement of the barrel in the unlocked mode is communicated to the door latch mechanism via the drive (7, 37), while rotation of the barrel in the locked mode operates the disengaging means (23) to disengage the drive.