Kentish Town Locksmiths Service Team
Local locksmith team
15 Jul 2026 12 min read
Your lock is playing up, you've just moved into a flat on Leighton Road, or you've had a break-in attempt — and now you're wondering whether you need to swap just part of the lock or replace the whole thing. It's a question that matters, because getting it wrong either leaves you overspending on work you didn't need or, worse, still vulnerable when you thought the job was done.
The honest answer depends on what type of lock you have, what's gone wrong with it, and what your insurer expects. This guide walks through every common scenario so you can have an informed conversation with a locksmith before anyone turns up at your door. Whether you're dealing with a tired Yale nightlatch on a Victorian terrace or a snapped euro cylinder on a uPVC front door in Kentish Town NW5, the distinction between changing the cylinder and changing the whole lock is easier to understand than most people expect.
## Cylinder vs. Lock Case: What Each Part Actually Does
Most front doors in the UK carry two distinct locking mechanisms. The first is a Yale-type nightlatch — a spring latch mounted on the door face that lets you pull the door shut behind you. The second is a 5-lever mortice deadlock set into the edge of the door, the type most home insurers ask for when they specify BS3621 compliance. uPVC and composite doors are different again: they typically use a multipoint lock driven by a central gearbox, operated through a euro cylinder — the oval insert you turn with a key. Each of these has a 'cylinder' or 'mechanism' element that can sometimes be swapped out independently, and a 'case' or 'body' that is fixed into the door itself.
The cylinder is essentially the barrel that reads your key and transmits the turning motion to the lock mechanism. The case or body is the housing bolted to or into the door, containing the levers, latch, bolts, and gearbox. When only the cylinder has been damaged, worn, or compromised — perhaps by a failed snap attack, a broken key, or a change of tenancy — a cylinder swap is usually sufficient. When the case itself is damaged, worn beyond adjustment, or simply not up to current standards, the entire lock unit needs to come out.
## When Changing the Cylinder Alone Is Enough — Lock Change London Scenarios
A cylinder-only replacement is the right call in several very common situations. If you've just moved into a rented flat or a purchased property and want to ensure previous key holders no longer have access, the cylinder is what needs to change — the case is almost certainly fine. The same applies after a break-in attempt where the door held but the cylinder shows signs of attempted snapping or drilling. In that case, you upgrade to an anti-snap, TS007 3-star rated euro cylinder and you're done. This is one of the most cost-effective security upgrades available to homeowners on uPVC and composite doors, and it directly addresses the most common forced-entry technique used on these doors across London.
[12] Many people ask how to change a door lock, expecting a complicated process. In the UK, what is known elsewhere as 'changing the cylinders' is simply swapping the euro cylinder for a new one keyed differently, or — with certain high-security systems — having the internal pin stacks reconfigured by a skilled locksmith. For a standard euro cylinder, a trained locksmith can remove the old one and fit a new one in under fifteen minutes once they are on site. The measurement that matters here is the cylinder size: you need to know the overall length from centre of the cam to each end (e.g. 35/45mm). If you are not sure, your locksmith will measure it on arrival. Do you need to change the lock when you move in? Generally yes — it is the simplest way to be certain you hold the only keys in circulation.
## When You Need the Whole Lock Replaced — Door Lock Replacement London
There are situations where swapping the cylinder simply isn't enough. If the lock case on a mortice deadlock has worn levers, a sprung bolt that no longer shoots cleanly, or damage from a forced entry, then the whole lock body needs to come out. The same is true if your existing mortice deadlock is an old two- or three-lever type and your insurer has asked for a BS3621 five-lever — you can't achieve that standard by changing just the cylinder, because five-lever mortice locks don't use a euro cylinder at all. Each lever inside the case must engage correctly with the key, and once those levers are worn or damaged, the whole unit goes.
Multipoint locks on uPVC doors present their own situation. If the gearbox — the central mechanism that drives multiple locking points up and down the door edge — has failed, you're looking at a full multipoint lock replacement, not just a cylinder change. Signs include a handle that turns but nothing engages, or a door that won't lock at all even after the cylinder is fine. For uPVC door lock repair London-wide, distinguishing between a cylinder fault and a gearbox fault is something a professional can usually diagnose in a few minutes. How do you measure a backset on a mortise lock? The backset is the distance from the edge of the door to the centre of the keyhole — typically 57mm or 65mm on UK doors — and your locksmith needs this to source the correct replacement case. It's also worth knowing when you're checking whether a mortice lock will fit your door.
## Combination and Digital Locks: Changing Codes Rather Than Hardware
Keypad and combination locks are increasingly common on internal doors, outbuildings, and some front doors. If you want to know how to change the code on a door lock, the process varies by brand and model, but most digital locks have a programming sequence accessed through a master code or a reset button — the manufacturer's manual is your first stop. How you change a combination lock code depends on whether it uses a dial mechanism or a push-button panel. Dial combination locks typically require you to turn to specific numbers in sequence to reach a change-code mode; push-button versions usually involve holding a reset button while entering a new sequence. If the manual has been lost or the lock is refusing to accept programming input, a locksmith can often carry out a factory reset or, where that's not possible, replace the lock unit entirely.
One scenario worth raising: if you've moved into a property that has a keypad lock and you don't know what codes the previous occupants set, you should treat it the same way as inheriting a standard cylinder lock — the codes need changing before the property is considered secure. How to change a combination lock that you've inherited from a previous occupant is worth asking about specifically when you call, because some older or lower-specification models don't support user-reprogramming and the whole unit may need replacing. If you're ever unsure, call 020 7871 7825 and describe what you have — we can usually advise over the phone before we even come out.
## What to Expect from a Professional Lock Assessment — Emergency Locksmith London
Whether you're locked out in NW5 at midnight or simply planning a security review after moving in, the process begins the same way: a qualified locksmith looks at the door, the frame, and the lock before recommending anything. On Kentish Town High Street and the surrounding streets — Fortess Road, Prince of Wales Road, and the terraced roads running off them — we see a mix of Victorian and Edwardian timber doors with traditional mortice locks, and more recent uPVC and composite replacements with euro cylinder multipoint systems. Each calls for a different approach, and no honest locksmith recommends a full lock change when a cylinder will do the job, nor fits a budget cylinder when the door genuinely needs a TS007 3-star upgrade.
As a 24 hour locksmith London homeowners and tenants can call any time — evenings, weekends, bank holidays — we confirm an exact, up-front quote on the phone before we set off. The factors that shape that quote are the lock type and specification you need, the time of day, travel to your postcode district, and any parts required. There is a call-out charge, as there is with any mobile trade, but the total is agreed before anyone comes out — no surprises on the doorstep. We send a locksmith straight away and are usually with you in about 30 minutes. For non-urgent work such as a planned cylinder upgrade or a lock assessment after a tenancy change, we can arrange a time that suits you during the day. If you're locked out London-wide or simply need advice on whether your door is up to what your insurer expects, call 020 7871 7825 — we're here around the clock.
## Choosing the Right Cylinder Grade: Anti-Snap, Anti-Pick, and TS007
Not all euro cylinders are equal, and the grade you choose matters far more than most people realise. A standard euro cylinder offers very little resistance to snapping — a technique where the visible part of the cylinder is broken off with a blunt instrument, exposing the cam and allowing the lock to be turned in seconds. Anti-snap cylinders include a deliberate break point engineered to snap away from the cam, rendering the technique useless. TS007 3-star cylinders go further, combining snap resistance with anti-pick, anti-drill, and anti-bump properties, and they are increasingly required or strongly recommended by home insurers for coverage to remain valid.
If you're on a uPVC or composite door anywhere in the Kentish Town area and your cylinder doesn't carry a 3-star or at minimum 1-star TS007 rating combined with a 2-star handle, your door is significantly more vulnerable than it needs to be. When a locksmith London resident trusts turns up and finds a standard cylinder, raising this point is part of a professional job — not a sales pitch. The upgrade from a standard to an anti-snap TS007 cylinder is one of the most straightforward and genuinely impactful security improvements available for a uPVC front door, and it doesn't require any work to the door itself beyond swapping the cylinder.
## Locked Out, Break-In Attempt, or Just Planning Ahead — Locked Out London
If you're currently locked out in London, the right first step is to check whether any other entrance to the property is accessible — a back gate left unlocked, a window left on the latch, or a spare key held by a neighbour or letting agent. If none of those options apply, do not attempt to force the door. Forcing a lock or frame without the right tools and knowledge risks expensive damage that turns a simple lockout into a full door repair. A trained locksmith can open most standard locks without damage to the door or frame using non-destructive methods — and if the lock does need to be drilled as a last resort, they will tell you before they proceed and confirm the cost of replacement on the spot.
After a break-in attempt — even one that didn't succeed — it's worth having the lock and door frame inspected before assuming everything is still secure. Attempted snap attacks often leave the cylinder slightly protruding or visibly deformed; attempted drilling leaves obvious marks. Neither necessarily means the whole door lock needs replacing, but it does mean the cylinder should come out and be replaced with a higher-specification upgrade. For upvc door lock repair London-wide following an attempt, we carry a range of anti-snap cylinders in common sizes to fit on the same visit, so you're not left waiting for parts. Call 020 7871 7825 any time — day or night — and we'll talk you through what's needed before we come out.
Frequently asked questions
[13] Do you need to change the cylinder when you move into a property?+
[14] In UK terms, yes — changing the cylinder is strongly advisable whenever you move into a property, whether purchased or rented. You have no way of knowing how many copies of the original key exist. A new euro cylinder, or a fresh 5-lever mortice lock keyed differently, means only you hold working keys from day one. Landlords and letting agents often do this between tenancies as standard practice, but if yours hasn't, it's worth requesting it or arranging it yourself.
How do you measure a backset on a mortise lock, and why does it matter?+
The backset is the horizontal distance from the edge of the door to the centre of the keyhole or spindle hole. On UK mortice locks it is most commonly 57mm or 65mm. It matters because a replacement lock case must match the existing backset — if it doesn't, the keyhole ends up in the wrong position relative to the escutcheon plate, and the lock either won't fit or won't operate correctly. To measure it, you use a tape measure from the door edge to the centre of the keyhole with the door open. Your locksmith will always check this on arrival before sourcing a replacement.
How do you change the code on a door lock or combination lock?+
For digital keypad locks, most models have a programming mode reached by entering a master or factory code followed by a sequence to set a new user code — the exact steps vary by model and are in the manufacturer's manual. For dial combination locks, changing the code typically involves opening the lock, turning the dial to a change setting, and following a specific sequence. Push-button combination locks usually have a reset function accessed from inside or via a tool hole. If the manual is lost or the lock won't accept programming, a skilled locksmith can often perform a factory reset on site or advise whether the unit needs replacing.
What factors determine the quote for a cylinder swap or full lock replacement?+
The main factors are the type and specification of lock or cylinder needed (a standard euro cylinder, an anti-snap TS007 unit, a BS3621 mortice lock, or a multipoint gearbox all sit at different specifications), the time of day (evenings, weekends and bank holidays are reflected in the call-out charge), travel distance to your postcode district, and whether the locksmith needs to carry specific parts or order them. We confirm an exact, all-inclusive price on the phone before we set off — there are no hidden additions when we arrive. If the job turns out to be different from what was described, we tell you and confirm any change before proceeding.
