Addiscombe Locksmith Service Team
Local locksmith team
14 Oct 2026 11 min read
If your home insurer has ever asked whether your front door has a BS3621 lock, you are not alone. It is one of the most common questions homeowners and tenants across Croydon raise when they are setting up or renewing a policy — and it is also one of the most misunderstood. The short answer is that a BS3621 lock is a British Standard-tested deadlock that meets a minimum security threshold most insurers recognise. The longer answer involves understanding what that actually means for your front door, your policy, and your peace of mind.
This guide cuts through the jargon. We will explain what BS3621 means, why insurers care about it, how to check whether the locks on your own front door already meet the standard, and what your options are if they do not. As your local locksmith Croydon team, we work on doors across CR0, CR2, CR7, and the surrounding postcodes every day — from Victorian terraced houses in Addiscombe and South Norwood to modern flats near East Croydon station — so the advice here is grounded in the real doors we see, not a generic checklist.
## What BS3621 Actually Means — and Why Your Insurer Asks for It
BS3621 is a British Standard specification for thief-resistant locks. Published by the British Standards Institution, it sets out a series of physical tests a lock must pass — resistance to picking, drilling, sawing, and manipulation — before it can carry the kitemark. The standard applies mainly to mortice deadlocks (the type that sits inside the door and throws a solid bolt into the frame) and to rim deadlocks (surface-mounted bolts sometimes used as secondary locks). When a lock earns the BS3621 kitemark, it means an independent laboratory has verified it can withstand a determined physical attack for a meaningful period of time.
Insurers ask for it because statistics back it up. Doors secured with a kitemarked lock are significantly harder to force in the time an opportunist burglar is willing to spend. Many home insurance policies include a clause stating that for a theft claim to be paid, all external doors must have been locked with a BS3621 or equivalent lock at the time of the break-in. If your front door only had a basic Yale-type nightlatch — a spring latch with no deadlocking feature — and a burglar simply slipped the latch or used a credit card to push it back, your insurer may decline the claim. That is not a hypothetical. It is a scenario we hear about from homeowners across Croydon who call us after the fact.
## How to Check Your Own Front Door Right Now
[8] Start by looking at the door itself, not the paperwork. Most traditional timber front doors in Croydon have two locks: a Yale-type nightlatch near the top of the door, and a mortice deadlock (sometimes called a mortice deadlock in older documents) in the middle. The mortice lock is set into the edge of the door and you will see a keyhole on both sides. To check whether it is BS3621, look for a small kitemark symbol — a capital K inside a circle — stamped or cast onto the lock faceplate on the edge of the door, or on the keyhole cover on the inside. You may need a torch. Alongside the kitemark you should see the number 3621. If you can see both, you have a BS3621 compliant mortice lock.
If your front door is uPVC or composite — the type with a long handle and a multipoint locking system — the situation is slightly different. These doors do not use a traditional 5-lever mortice lock. Instead they use a euro cylinder (the small oval barrel the key goes into) operating a multipoint mechanism with multiple hooks and bolts. For this type of door, the relevant standards are TS007 and BS EN 1303, and the cylinder quality matters enormously. Specifically, anti-snap cylinders are strongly recommended, because euro cylinders can be snapped at the groove line in a matter of seconds with simple tools — a technique that has been common in burglaries across South London for years. A TS007 3-star cylinder (or a 1-star cylinder combined with a 2-star door handle) offers equivalent resistance. Check the cylinder itself for a star rating or kitemark, or look at any paperwork that came with the door. If you are uncertain, the safest step is to call us and we can carry out a quick door security assessment.
## Common Scenarios: When Locks Fail to Meet the Standard — Lock Change Croydon
We carry out lock change Croydon work week in and week out, and several patterns come up repeatedly. The first is the door with an old 2-lever mortice lock. Many older Croydon properties — particularly mid-century council-built houses and conversions — still have 2-lever locks that were fitted decades ago. A 2-lever lock offers very little resistance and will not meet BS3621, which requires a minimum of 5 levers. Replacing it with a new 5-lever BS3621 mortice deadlock is a straightforward job that makes a genuine difference to both your security and your insurance position.
The second common scenario is the uPVC door with a standard euro cylinder. Many uPVC doors were fitted with basic cylinders that offer no anti-snap protection. After a spate of burglaries that targeted exactly this vulnerability, door lock replacement Croydon enquiries for upgraded anti-snap cylinders increased noticeably. The good news is that swapping a euro cylinder is usually quick; the door lock replacement itself does not require removing the door or the multipoint mechanism. We confirm the exact specification of your existing lock before we order or bring parts, and we give you an up-front price on the phone before anyone comes out — the final quote reflects factors including the type of cylinder required, the door construction, and when the work is being carried out. If you are unsure whether your uPVC door lock meets your insurer's requirements, call 020 4542 3118 and describe what you can see — we will tell you honestly whether a visit is worthwhile.
## UPVC Door Lock Repair Croydon — When Repair Is Better Than Replacement
Not every lock problem means you need a full replacement. uPVC door lock repair Croydon calls are often for mechanisms that have become stiff, misaligned, or difficult to operate — common on doors that have dropped slightly on their hinges over time, which causes the multipoint bolts to drag against the keep plate in the frame. In many cases, adjusting the hinges and realigning the door resolves the stiffness without touching the lock mechanism at all. This matters from an insurance perspective too: a lock you cannot throw properly because it is stiff is a lock you may stop bothering to use, leaving the door effectively unsecured.
Where the multipoint mechanism itself has failed — broken springs, snapped gearbox, stripped cam — repair or replacement of the mechanism is the right route. We carry a range of common multipoint lock mechanisms on the van so that most uPVC door lock repairs can be completed on the same visit. After any repair we always check that every locking point engages cleanly and that the cylinder, if present, is performing correctly. If we find the cylinder is a standard non-anti-snap type, we will flag it and explain the upgrade option — but we will never carry out work you have not asked for or agreed to.
## Locked Out, Emergency Locksmith Croydon, and What to Do First
Even the best locks on your door are of limited comfort if you are standing outside them at 11pm having left your keys inside. As an emergency locksmith Croydon service, we are called out to exactly this situation across the area every week — in Thornton Heath, Selhurst, Shirley, New Addington, and Purley as well as central Croydon. Before you call, run through a quick checklist: is there a spare key with a trusted neighbour or family member nearby? Is there a back door or other entrance you can access safely without damaging anything? Is there any chance the door is not fully locked — just pulled shut on the nightlatch — in which case the person with the spare key can let you in without a locksmith at all.
If none of those options apply, we are your next call. As a 24 hour locksmith Croydon service, we operate around the clock including evenings, weekends, and bank holidays. When you call 020 4542 3118, we will confirm an up-front price before we set off — no surprises at the door. The price reflects your location, the type of lock on your door, the time of day, and the parts or method needed. We send a locksmith straight away and are usually with you in around 30 minutes. We will always ask you to verify that you are the occupant or owner before any work begins — this is standard practice and protects everyone.
## Making Your Home Insurance Work for You: Practical Next Steps
Once you know your locks meet BS3621 or the equivalent standard for your door type, it is worth documenting it for your insurer. Take a photograph of the kitemark on your lock faceplate or cylinder. Keep any receipts or job reports from lock installation work — we provide written confirmation of the locks fitted on every job. When you renew your policy, you can answer the lock-type question accurately and confidently, which removes any ambiguity about whether a future claim would be covered.
If you are a landlord or letting agent managing properties in the Croydon area, this matters even more. Tenants rely on you to ensure the doors meet a reasonable security standard, and many landlord insurance policies have the same BS3621 requirements. After a tenancy ends and keys are returned, upgrading the cylinder or changing the lock entirely is good practice — it ensures the outgoing tenant no longer has a working key, and it gives the incoming tenant confidence in their new home. We work with landlords and letting agents across Croydon on exactly this basis, and our mobile locksmith service means we can attend at a time that suits the handover schedule.
Frequently asked questions
My insurer says I need a BS3621 lock — but my front door is uPVC. What do I do?+
uPVC doors with multipoint locking mechanisms do not use a traditional 5-lever mortice lock, so they cannot carry a BS3621 kitemark in the same way. Most insurers accept a TS007-rated anti-snap euro cylinder combined with a multipoint mechanism as the equivalent. The key step is to check the star rating on your cylinder and confirm with your insurer what they specifically accept. If you are unsure, call us on 020 4542 3118 — we can assess your door and tell you exactly what you have and what, if anything, needs to change to satisfy your policy conditions.
How do I know if my existing mortice lock is BS3621 without calling anyone?+
Look at the edge of the door where the lock faceplate sits. You are looking for the BSI kitemark — a stylised letter K inside a circle — alongside the number 3621 stamped into the metal. It may be small and you may need a torch to see it clearly. If the mark is there, your mortice lock meets the standard. If the faceplate is unmarked, or if you can only count two key positions when you turn the key (indicating a 2-lever lock), it almost certainly does not meet BS3621 and is worth replacing. A 5-lever BS3621 mortice deadlock is a standard job for any qualified locksmith.
If I am locked out, will the locksmith damage my lock or door to get in?+
A skilled locksmith will always try the least destructive method first. For many nightlatches and euro cylinder locks, non-destructive entry is possible. For some high-security locks — including well-fitted BS3621 mortice locks, which is part of the point — non-destructive entry may not be possible, and in those cases drilling the cylinder and fitting a new one is the standard approach. We will always explain the method and the likely outcome before we begin, and we will confirm all costs up front. The final price depends on the lock type, the entry method required, and any parts needed.
Do I need to change my locks after moving into a new home in Croydon?+
Yes, as a precaution it is always advisable. You have no way of knowing how many copies of the existing key are in circulation — previous owners, former tenants, estate agents, or tradespeople may all have had keys cut at some point. Changing the cylinder on a uPVC or composite door, or replacing the mortice lock on a timber door, removes that uncertainty entirely and gives you a fresh start. It also gives you the opportunity to upgrade to a BS3621 or anti-snap standard if the existing locks do not already meet it, which helps with your home insurance from day one.
