Nightlatches & Rim Locks
Operated externally by a key and internally by a handle or knob, nightlatches & rim locks are a convenient way of locking a door closed and are available in wide choice styles, finishes and operations including deadlocking and non-deadlocking.
Don't forget, most insurance policies require that at least one lock on a final exit door be fitted with a British Standard lock. If you are fitting a nightlatch in conjunction with a mortice lock, make sure one of them as met the required standard.