Earlsfield Locksmith Service Team
Local locksmith team
15 Jul 2026 13 min read
Your front door takes a battering — keys worn smooth, a recent break-in attempt, a tenancy change, or a lock that simply refuses to turn smoothly anymore. The question that follows is almost always the same: do I need a whole new lock, or just the cylinder? Getting that wrong costs time and money. A full lock replacement when only the cylinder needed swapping is unnecessary work; leaving a compromised lock case in place when the whole mechanism is failing is a security risk. This guide walks you through the difference in plain terms, so that when you call a locksmith London homeowners trust, you already have a clearer picture of what the job is likely to involve.
Earlsfield Locksmith covers the whole Wandsworth area — from the terraced streets off Garratt Lane to the mansion flats near Wandsworth Common, the purpose-built blocks along the river, and the Victorian semis tucked behind Earlsfield station. We work on all residential door types, 24 hours a day, and we give you an exact price before any work begins.
## Cylinder vs. Lock Case: Understanding What You Actually Have
Most front doors in the Wandsworth area use one of two main locking systems, sometimes both together. A Yale-type nightlatch — the kind you pull shut behind you — has a small oval or round cylinder that sits in the edge of the case and operates a spring-loaded latch. A 5-lever mortice deadlock is the thicker lock set into the door itself, with a keyhole rather than a barrel visible from outside; this one has an internal mechanism called the case, and the levers inside it do the security work. On modern uPVC and composite doors, you will instead have a multipoint lock: a long strip of shoot-bolts and hooks all operated by lifting the handle and turning a single euro cylinder. That cylinder — roughly 30 to 90 mm in total length, sitting in the centre of the door — is what you can swap independently of the mechanism behind it.
[13] Knowing which type you have tells you immediately whether a simple cylinder change is an option. On a mortice deadlock the cylinder is not a separate component in the same way — the levers are the security element, and changing the lock (which in UK practice means swapping to a new cylinder or having a locksmith repin the existing one) is less straightforward than on a nightlatch or euro cylinder door. On a uPVC door, the euro cylinder is almost always independently replaceable within minutes once you know the correct size.
## When Changing the Cylinder Is Enough — and How to Get It Right
[14] Swapping the cylinder alone makes sense in a clear set of circumstances: you have moved into a new property and want to know that previous occupants cannot walk back in; a tenant has left and not returned all keys; a key has been lost or stolen but the lock case itself is undamaged; or you want to upgrade to an anti-snap, TS007 3-star rated cylinder without changing the entire door furniture. In each of these situations the lock body is perfectly sound — only the key profile needs to change. Many homeowners ask how to change a door lock cylinder and expect a complicated answer. In practice, for a euro cylinder, the process is straightforward: measure the cylinder, order the correct size, remove the single retaining screw from the face of the door edge, turn the old cylinder out with a key, slide the new one in and re-secure the screw. A trained locksmith completes this in a few minutes per door.
The critical step that trips people up is measuring correctly. To get the right cylinder, you need the distance from the centre of the retaining screw hole to each end of the cylinder — the outer (street-facing) half and the inner (hallway-facing) half. If you are measuring a mortice lock and asking how do you measure a backset on a mortise lock, what you are actually finding is the distance from the face of the door to the centre of the keyhole; this tells you which replacement lock case will fit the existing door pocket without additional chiselling. If your door is a standard 44 mm uPVC slab with equal 35/35 halves you will find cylinders readily available, but older timber doors or non-standard profiles often need measured replacements. Getting this wrong means either the cam does not reach the mechanism or the cylinder protrudes — and a protruding euro cylinder is precisely what makes a door vulnerable to the snap attack that is common on roads like Lydden Road and similar residential streets across SW18 and SW17.
## When the Whole Lock Needs Replacing — Lock Change London Scenarios
There are situations where swapping the cylinder is not enough, and proceeding as though it is can leave your home less secure than you realise. The lock case must be replaced when: the mechanism is visibly damaged after a break-in attempt — bent shoot-bolts, a sprung case, or levers that have been manipulated will not be fixed by a new cylinder alone; the lock has simply worn out and the key turns but the bolt no longer engages the keep reliably; you are upgrading from a cheap or unrated lock to one that meets BS3621, which many home insurers now require for a valid policy on a main entrance; or the door has been changed and the existing lock no longer lines up with the frame keep. A door lock replacement London homeowners sometimes delay can also become urgent when a multipoint lock mechanism on a uPVC door fails mid-operation — the door is locked, the handle lifts but nothing engages, and you are either locked in or locked out. That is a mechanism failure, not a cylinder issue, and it needs a full gearbox or mechanism replacement.
Composite and uPVC door lock repair London calls are some of our most common jobs across Wandsworth. The multipoint gearbox — the internal strip that drives all the hooks and bolts — is a wearable part. On a door that is slammed regularly, or one where the alignment between door and frame has shifted slightly as the building settles, the gearbox takes enormous stress every single day. A replacement gearbox needs to match the brand and size of the existing mechanism; this is why a professional locksmith measures the door before ordering parts rather than arriving with a generic unit. We confirm an exact up-front price on the phone before we come out, based on the door type, the lock specification required, the time of call, and travel.
## uPVC Door Lock Repair London and Locked Out London: Knowing What to Do in an Emergency
If you find yourself locked out London — whether from your flat, your house, or a communal entrance — the first step is always to check for a spare key with a trusted neighbour, family member, or your letting agent or managing agent if you rent. Check that every other entrance is genuinely secured before you assume the front door is the only way in. If you are a tenant, your landlord or housing association may hold a master key. Never attempt to force or manipulate a lock yourself: beyond the obvious risk of damage that makes the eventual locksmith job considerably more involved, it can also raise questions about ownership that a professional will need to resolve anyway. A skilled locksmith will verify your right of access before beginning work — this protects you as much as it protects the property.
When those options are exhausted, call 020 3757 5840 and we will send a locksmith straight away. We are usually with you in about 30 minutes across the Wandsworth area. As a 24 hour locksmith London team, we work evenings, weekends, and bank holidays at the same quality standard — a lock opened at 2am on a Sunday is handled with exactly the same care as one opened on a Tuesday morning. Once you are back inside, we can assess the lock that failed and advise whether a cylinder change, a mechanism replacement, or a full door lock replacement is the appropriate next step. We never recommend more than the job genuinely requires.
## Combination Locks, Smart Locks, and Changing Access Codes — What Changes and What Stays the Same
Some homeowners have moved to combination-style or digital door locks, particularly on rear garden doors, outbuildings, or as a secondary lock on a flat entrance. The question of how do you change the code on a door lock — or how do you change a combination lock code — depends entirely on the brand and model. Most combination deadlocks sold in the UK have a reset procedure that involves holding a reset button (often inside the battery compartment or behind the cover plate) while entering a new sequence. How do you change a combination lock in practice varies: some require the existing code to be active during the reset, others require a factory reset tool. The manufacturer's instructions are the only reliable guide for a specific unit. If those are lost and you cannot find the model number to look them up, a locksmith can often identify the lock and advise — or, where the lock is no longer functioning correctly, recommend a suitable replacement.
[15] Smart locks and keypads introduce a different question: do you need to change the lock when you install one? With a traditional cylinder, the answer is no — a new cylinder has never had keys cut from it and comes with its own fresh set. With a smart lock that uses a code, changing the code on first installation is the equivalent step, and yes, you should always do this before treating the installation as complete. Where a smart lock retains a physical cylinder backup, that cylinder should also be new or freshly changed so that the two access methods are equally secure. If you are unsure whether your existing smart lock setup is correctly configured after a move or tenancy change, we are happy to take a look and advise.
## What Earlsfield Locksmith Covers Across the Wandsworth Area
As a fully insured, mobile emergency locksmith London service based in and around Earlsfield, we cover all of SW18, SW17, SW12, and the wider Wandsworth borough. Our work includes: euro cylinder replacement on uPVC and composite doors; anti-snap cylinder upgrades to TS007 3-star specification; nightlatch replacement and repair; 5-lever mortice deadlock supply and fitting to BS3621; multipoint lock gearbox replacement on uPVC and composite doors; door lock replacement London-wide across the borough; upvc door lock repair London calls for failed mechanisms and misaligned doors; emergency lock opening without damage where possible; lock change London after break-in or attempted forced entry; boarding up after a failed door; communal door lock replacement for blocks of flats; deadlock fitting to timber rear doors; door alignment adjustment where a dropped hinge causes lock strain; lock replacement following a lost or stolen key; upgrading locks at the request of a letting agent or housing association; lock assessment and report for insurance compliance; installation of British Standard-rated locks; full door furniture change including handles and escutcheons; fitting additional locks where a second point of security is needed; nightlatch conversion to a double-cylinder model for added security; lock snapping damage repair and cylinder replacement; installation of door reinforcement hardware alongside a new lock; non-destructive entry for residential lockouts across the borough; lock replacement advice for landlords after a tenancy change; and same-visit cylinder measurement, supply, and fitting. The final price depends on the lock type, specification, time of call, and any parts needed — we confirm everything before work begins.
Whether you are on a Victorian terrace near Wandsworth Town station, in a flat above one of the shops on Garratt Lane, or in a newer development closer to Young's Ram Brewery on Wandsworth High Street, the right lock decision starts with the right diagnosis. Call 020 3757 5840 — we answer 24 hours a day, every day of the year, and we will talk you through what your door needs before anyone sets off.
Frequently asked questions
How do you change the lock, and is it possible on all UK door types?+
In UK locksmith practice, changing the cylinder generally means fitting a new cylinder (or having an existing cylinder repinned) so that old keys no longer work and new ones do. It is straightforward on doors that use a euro cylinder — the type found in virtually all uPVC and composite doors — because the cylinder is a standard replaceable component. On a traditional 5-lever mortice deadlock, the levers are the security element rather than a removable cylinder, so the equivalent process is to replace the whole lock case, which gives you a new key set. A Yale-type nightlatch sits somewhere in between: the cylinder can often be replaced, but the lever mechanism inside the case also wears and may need attention at the same time. A trained locksmith will assess which applies to your door and confirm the approach before starting.
Do you need to change the locks when you move into a property?+
Yes — this is one of the most important steps a new homeowner or tenant can take. A new lock comes with keys that have never been copied, but if the lock or cylinder was not changed before you moved in, you have no way of knowing how many copies of the existing key are in circulation. Previous owners, former tenants, contractors, and estate agents may all have had keys cut. Fitting a new cylinder (on a uPVC or composite door) or a new lock case (on a timber door with a mortice lock) means only the keys in your possession will work from that point on. This is especially important if you are moving into a property that has been let through a managing agent or has had multiple previous occupants.
How do you measure a backset on a mortise lock — and why does it matter when replacing a lock?+
The backset on a mortise lock is the distance measured from the face of the door (the edge you can see when the door is open) to the centre of the keyhole. You measure it with the door open, running a tape measure horizontally from the door face to the middle of the keyhole on the door's surface. This measurement is critical because a replacement lock case must match the existing backset, otherwise the new keyhole will not align with the keyhole cover on the door face, and in some cases the lock will not physically fit the pocket already cut into the door. Standard backsets in the UK are typically 45 mm or 57 mm on timber doors, but older properties sometimes have non-standard dimensions — which is one reason a locksmith measures before ordering, rather than arriving with a standard unit and hoping for the best.
What determines the final price for a cylinder change or lock replacement?+
The final price depends on several factors: the type of door and lock (a euro cylinder swap on a standard uPVC door is a simpler job than replacing a multipoint gearbox on a composite door, for example); the specification of the replacement parts required (a TS007 3-star anti-snap cylinder costs more than a basic unit, and rightly so given the security difference); the time of call, since evening, weekend, and bank holiday work involves different overheads; and travel distance within our coverage area. We confirm an exact price on the phone before we come out — there are no surprises on the invoice. If the job turns out to be different from what was described once we see the door, we will explain why and confirm any revised price before proceeding.
