Kentish Town Locksmiths Service Team
Local locksmith team
7 Oct 2026 11 min read
If you look at most front doors in Kentish Town — whether it is a Victorian terrace off Fortress Road, a converted flat on Leighton Road, or a newer build near Kentish Town West station — you will likely spot two locks. There is the one you flick open automatically every time you come home, and there is the chunkier one lower down that you turn with a proper key. They are not duplicates; they do completely different jobs. Understanding which is which, how each one works, and why most insurers want you to have both is the kind of knowledge that can save you a ruined door, a refused insurance claim, or a very anxious night.
This guide explains what a mortice lock is, how it differs from a nightlatch (sometimes called a Yale lock), and what to do when either one lets you down. Whether you have just moved into a new place and want to understand what you are dealing with, or you are trying to decide whether your front door is as secure as it should be, read on.
## What Is a Mortice Lock, and Why Does It Live Inside the Door?
A mortice lock — sometimes spelt mortise lock — is a lock that sits inside a pocket, or mortice, cut into the edge of the door itself. Because the lock body is entirely recessed into the timber, it cannot simply be unscrewed from the outside, and the bolt is driven by turning a key rather than by any spring mechanism. When you turn the key, a series of internal levers align to allow the bolt to move; when they do not align — because the wrong key is inserted — the bolt stays put. That resistance is the core of its security.
In the UK, mortice locks are almost always mortice deadlocks, meaning the bolt has no spring: it stays in whichever position the key last left it. The number of levers matters enormously here. A 2 lever mortice lock offers very basic security and is really only suitable for interior doors or low-risk applications like a garden shed. A 5 lever mortice lock is a different proposition entirely — five levers mean many more possible key combinations and far greater resistance to picking and manipulation. Most home insurance policies in the UK require a 5 lever mortice lock that meets British Standard BS3621 on any external door. If yours does not meet that standard, it is worth checking your policy wording, because a claim could be complicated if a burglar forces a substandard lock.
## How a Nightlatch Works — and What Makes It Different
A nightlatch — often called a Yale lock after one of the most recognisable brands — works on an entirely different principle. The lock body is mounted on the surface of the inside of the door, not sunk into it, which is why it is also known as a rim lock (and its cylinder, the part that accepts the key, is called a rim cylinder). The latch bolt is spring-loaded, meaning it shoots out automatically every time the door closes. That is the satisfying click you hear when you pull your front door shut. From the outside, you turn your key to retract the latch; from the inside, there is usually a knob or lever that lets you open it without a key at all.
This spring-loaded convenience is also the nightlatch's limitation. Because the latch relies on a spring rather than a deliberate key turn, it can sometimes be manipulated more easily than a mortice bolt. More importantly, if someone inside the property puts the nightlatch on the snib (a small catch that holds the latch retracted), the door will not lock when it closes — a surprisingly easy mistake to make. A nightlatch alone is generally not considered sufficient security by insurers for an external front door. It is fast and convenient, but it is designed to work alongside a mortice deadlock, not instead of one.
## Two Locks Together: Why Most UK Front Doors Have Both
The combination of a nightlatch at the top and a 5 lever mortice lock lower down is the traditional British answer to front-door security, and it has stood the test of time for good reason. The nightlatch gives you everyday speed — you can come and go quickly without fumbling for the deadlock key every single time. The mortice lock is what you engage last thing at night and whenever you leave the house for more than a few minutes. Together they address different attack methods: the nightlatch resists casual pushing and sneak-through, while the mortice bolt makes forced entry and picking significantly harder.
On uPVC and composite doors — now common in Kentish Town's newer builds and housing association properties — the arrangement looks different but achieves the same aim. These doors typically have a multipoint locking system operated by lifting the handle and turning the key, throwing bolts at multiple points around the frame simultaneously. The key-operated cylinder on a uPVC door is a euro cylinder, and it carries its own specific risk: cylinder snapping. A burglar can snap a cheap euro cylinder in seconds with basic tools, exposing the mechanism inside. Anti-snap cylinders, ideally carrying a TS007 3-star rating, close that vulnerability and are well worth specifying if you are having a lock change London. If you are unsure which type of cylinder your uPVC door has, a quick call to our team will give you a straight answer.
If you are in any doubt about the security of your front door — or if you have recently moved in and want the locks changed so that only your keys work — give us a call on 020 7871 7825. We are out on the road 24 hours a day, covering Kentish Town and the surrounding area, and we can assess your door and recommend what it actually needs rather than what is simply easiest to fit.
## What Happens When Either Lock Fails — Locked Out London and What to Do Next
Getting locked out of your home is more common than most people expect, and it rarely happens at a convenient time. The first sensible step, before anything else, is to check whether you have a spare key with a trusted neighbour, friend, or family member nearby. It is also worth checking every entrance to the property calmly — a back door or ground-floor window that was left on the latch. If you live in a flat, speaking to a managing agent or caretaker may also open up options. Those are the legitimate, safe checks. What you should not attempt is any kind of forced entry yourself: a misguided shove can split a door frame, buckle a multipoint locking system, or break a uPVC door beyond repair — all of which costs far more to put right than a locksmith call-out.
A skilled locksmith will almost always be able to open a door non-destructively, using techniques that leave both the door and the lock intact. When destruction is unavoidable — for example, if a lock has seized completely — a qualified locksmith will carry replacement parts and can carry out door lock replacement London on the same visit, so you are not left with an insecure property. At Kentish Town Locksmiths, we send a locksmith straight away when you call and are usually with you in about 30 minutes. We will confirm an exact up-front price on the phone before anyone sets off, so you know exactly what to expect. The final cost depends on factors such as the type of lock involved, the parts needed, and the time of day — evening, weekend, and bank holiday call-outs are priced accordingly, and we are transparent about that from the outset.
For upvc door lock repair London, the same principle applies. A failed multipoint mechanism, a snapped euro cylinder, or a handle that no longer lifts the locking bolts are all common faults — and all repairable by an experienced locksmith who carries the right stock. We work across the full range of door types found in Kentish Town, from original Victorian timber doors to modern composite and uPVC frames.
## Keeping Your Locks in Good Shape — Practical Advice for Kentish Town Homes
Locks are mechanical devices that benefit from occasional attention. A mortice lock that feels stiff can usually be helped with a light application of graphite powder — not oil or WD-40, which attracts dirt and can gum up the levers over time. A nightlatch that does not click shut cleanly may have a latch bolt that has started to wear, or the door frame may have shifted slightly (common in older Kentish Town terraces where seasonal timber movement is noticeable). Catching these small faults early is much cheaper than dealing with a lock that fails entirely on a cold Sunday night.
If you move into a new flat or house, changing the cylinder of a nightlatch and the lock barrel of a mortice lock is straightforward and genuinely important. You have no way of knowing how many keys were cut during the previous tenancy or ownership. Landlords and letting agents are often surprised by how quick a lock change London actually is — in most cases it takes under an hour per door and causes minimal disruption. If you are a tenant, check your tenancy agreement and speak to your landlord first; most are happy to arrange it. As a 24 hour locksmith London, we can also help with emergency lock changes after a break-in, a lost key, or a relationship breakdown where access security becomes urgent.
## Knowing Your Locks Helps You Make Better Decisions
Understanding the difference between a mortice lock and a nightlatch is not just an academic exercise. It helps you have a more informed conversation with a locksmith, understand what your insurer is actually asking for, and make smarter choices when upgrading or replacing hardware. A well-fitted 5 lever mortice lock and a quality rim cylinder on the nightlatch — or a TS007-rated euro cylinder on a uPVC door — are genuinely effective deterrents. Burglars, like most people, follow the path of least resistance, and a properly secured door sends them elsewhere.
If you have questions about what locks are on your front door, whether they meet insurance requirements, or what a lock change or repair would involve for your specific door, we are always happy to talk it through. Kentish Town Locksmiths is a fully insured, experienced mobile locksmith service operating across Kentish Town and the wider area as a trusted locksmith London. Call 020 7871 7825 — we answer 24 hours a day, every day of the year, including bank holidays.
Frequently asked questions
[5] What is the difference between a mortice lock and a deadlock?+
[6] In the UK, the correct term is a mortice deadlock rather than deadlock, which is an American expression. They refer to the same basic principle — a bolt that moves only by key action with no spring mechanism — but UK mortice deadlocks are specifically graded by lever count, and the British Standard BS3621 is the benchmark most UK insurers refer to. A 5 lever mortice lock meeting BS3621 is what most policy documents mean when they require a deadlock on an external door.
Is a nightlatch the same thing as a rim lock?+
Yes, essentially. A nightlatch is a surface-mounted spring-latch lock fitted to the inside face of a door. Because its body sits on the rim of the door rather than inside it, the whole assembly — including the cylinder on the outside and the latch body on the inside — is called a rim lock. The cylinder itself is specifically a rim cylinder, as opposed to the euro cylinder found on uPVC and composite doors. The terms nightlatch, Yale lock, and rim lock are all used to describe the same type of fitting in everyday conversation.
My front door has a uPVC door with just one keyhole — do I still need a mortice lock?+
On a uPVC or composite door with a multipoint locking system, you do not normally fit a separate mortice lock, because the multipoint mechanism already throws bolts at several points around the frame when you lift the handle and turn the key. What matters most on these doors is the euro cylinder quality. A standard euro cylinder can be snapped quickly with simple tools; an anti-snap cylinder rated to TS007 3-star closes that gap. If you are unsure what cylinder your door has, we can check it and replace it on the same visit if needed. We confirm an exact price before any work begins.
How do I know if my locks meet my home insurance requirements?+
Most UK home insurance policies require a 5 lever mortice lock to British Standard BS3621 on all external timber doors, and an anti-snap euro cylinder on uPVC or composite doors. The easiest starting points are to look at the face of the mortice lock — if it carries a British Standard kite mark, it is likely compliant — and to check your policy schedule, which should specify exactly what standard is required. If you are still unsure, call us on 020 7871 7825 and we can inspect your existing locks and advise clearly on what, if anything, needs upgrading.
