Stand at your front door with the key in your hand and you are looking at one of three families of lock — and which family it is decides everything else: how secure the door can be, what an insurer expects of it, what goes wrong with age, and what an upgrade costs. Plenty of articles list lock types; this one starts where you actually start, at the door, identifying what you own, then tells you what that means in practice.
Many timber doors carry two of these, a nightlatch up top for convenience, a mortice deadlock below for security, the difference between the two is covered in mortice vs rim locks. That pairing is a feature, not a redundancy.
How it works: turning the key rotates a cam that drives hooks, bolts and rollers along the full door edge into the frame, engaged by lifting the handle first. Locked properly, a multipoint door grips the frame at several points, which is excellent against force.
The honest weakness sits in the cylinder itself: a standard one snaps under leverage in seconds, which is why the ratings, TS007 three-star, Sold Secure SS312 Diamond, exist and why our anti-snap guide is the companion piece to this one. The other failure we attend constantly is mechanical: gearboxes wear, doors drop, and a handle that needs a shoulder to lift is a breakdown announcing itself. Serviced early, it is a small job; forced until it snaps, considerably more.
What insurers expect: usually "key-operated multi-point locking", satisfied by the door itself, with the smart money (and some policies) now also caring about the cylinder's rating.
How it works: a lever pack inside the door throws a solid deadbolt into the frame. No springs to slip, nothing to reach from a broken pane, with the key out, there is simply nothing to operate. It is the configuration insurers grew up with, which is why timber-door policy wording still says "five-lever mortice deadlock to BS3621".
The honest weaknesses: lever count is not the whole story, a five-lever lock without the Kitemark lacks the hardened bolt and anti-drill plates the standard tests for. And a deadlock only works when turned: a mortice key that lives in a drawer protects the drawer. Age shows as a stiff, gritty turn, usually wear or a dropped door, and worth a service before a key snaps off in it.
How it works: a spring latch grabs as the door closes, self-locking convenience, which is exactly its limit. A basic nightlatch alone is a latched door, not a deadlocked one, and older models are vulnerable to slipping and to being opened through a letterbox or adjacent glass.
Done properly: modern deadlatching and BS-rated nightlatches lock the latch against slipping and can deadlock the handle, a genuine security component, especially paired with a mortice deadlock below. If your nightlatch predates living memory, replacing it with a deadlatching equivalent is one of the cheapest meaningful upgrades a timber door can have.
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Every family upgrades in place. uPVC/composite: a rated, correctly sized cylinder, minutes per door. Timber: a Kitemarked mortice lock in the existing case size, a deadlatching nightlatch, or both. Listed buildings and period doors: sympathetic rated hardware exists, and a locksmith who works on old doors will know it. None of these jobs needs a new door; all of them are quoted as one fixed figure before work starts — and if you are not sure what you are looking at, a photo of the lock face and the door edge is usually enough for us to tell you over the phone.
Most comparisons skip the question that decides everything for a British home: will it fit your multipoint door at all? A working locksmith's view — where smart wins, where mechanical wins, the insurance angle, and the hybrid setup we actually recommend.
For the jobs best left to a pro, your local locksmith network has you covered nationwide.
Real 2026 UK numbers from inside the trade: a full price table, hourly rates by time of day, VAT explained, and the call-out fee trap that catches people out.
Honest 2026 numbers, lock by lock and for the whole house. What each door costs, the cylinder-only saving most people miss, and whether rekeying beats replacing.