A night latch is one of the most popular types of lock that’s used in residential properties with wooden doors. These locks are simple yet very effective in providing basic security for homes, but if your in a rush and forget your keys inside the house and close the door, then you're locked out! This price is for opening only. Not replacing. A new cylinder may be approximately £20 - £30 on top of this price. This should only be needed if the lock is damaged or if you have no spare keys.