A night latch is a lock that can only be opened with a key from the outside and, as long as its not a double locking version, it can always be opened from the inside. The latch can be held open with the use of the snib or it can be locked closed with the snib stopping key operation from the outside.
Some night latches have the ability to be double locked, I think this was designed for when the door has a glass panel this prevents am intruder breaking the glass and putting their hand through and using the lever to open the door. The downside to this is that anybody left in the property can not get out through that door and it is possible to accidently turn the key from the outside whilst removing your keys and if the door is slammed you could be locked in!
In my opinion the night latch is best not double locking as it is a lock that is ideally suited to be used during the day, your insurance company will usually asked for an additional British Standard lock.
A deadlock is a lock that requires a key to lock it from either side, your insurance company will ask for a 5 lever British Standard deadlock, this is identified by the British Standard logo. Dead lock sometimes have a latch operated by a lever above them, these are called Sash locks and should also be certified to British Standard.
In my opinion these locks should be used whenever you are out, at night and/or feel vulnerable.
There are many different types of MPL’s.
A MPL that is fitted to a front door should be configure so that only a key will withdraw the latch, this give a level of protection every time the door is closed. However not all MPL’s are capable of this, an easy way to tell is by putting a key in from the outside and when turned if the latch is withdrawn then it should be possible to change the handle configuration and allow this.
Roller Mushroom Deadbolt Pin Hook & Anti- lift pin
Rollers are primarily used to pull a door in tight and prevent drafts, I don’t think they offer much protection, but I think insurance companies may still class them as a locking point. Mushroom also help to pull a door in tight and offer more security than the roller. Dead bolts are good depending how far they go into the door frame the same applies for Pins. In my opinion the Hook with the anti-lift pin provides the best security as long as it is aligned correctly, the hook goes in behind the keep and the door cannot be forced up or down to get it out.
Service Note – if you have to force the handle up to be able to turn the key, then the mechanism is out of alignment and when you are forcing the handle up the locking mechanism is taking the weight of the door, which it is not designed to do and will eventually break. They usually break in the closed position so its well worth getting the lock serviced and realigned ASAP, they can also be slackened off to help elderly people with arthritis.
At present most insurance companies are happy with just 3 locking points.
All these locking points are held in place with an interchangeable lock Cylinder and despite your insurance company not requesting any standard on these (yet) they vary in quality and levels of security.
There is a practice called “lock snapping” used by burglars which takes advantage of a weakness in the lock cylinder.
The practice involves snapping the lock cylinder in half, if an incorrect size cylinder is fitted then there might be enough of the cylinder protruding not to need to remove the bottom of the handle away to get purchase on the cylinder.
The only cylinders that I recommend is a 3 star British standard cylinder, and this is why.