The Clip that retains the door locks on  TR5.250 and 6 and other cars of the period use that use the same type of lock, retained by a clip often fail. In time the aperture in the door skin that located the lock, wears such that the clip can no longer retain the lock.  A solution is at hand, part number 714599IMP is a kit of parts that solidly clamp the lock to the door.