BS3621 Insurance-Approved Locks in Bayswater & W2

What BS3621 means, why insurers ask for it, and fitting insurance-approved mortice deadlocks and nightlatches in Bayswater flats, W2 and Queensway.

Open 24/7 · Mobile service-area business — we come to you. No shop and no visitor address.

24 hours a day, 7 days a week

Bayswater, Queensway and the W2 districts

Mobile service-area business — we come to you. No shop and no visitor address.

What BS3621 covers, in short

A BS3621 lock is a mortice deadlock or nightlatch that has been independently tested against a British Standard for resistance to picking, drilling and forced attack. It is stamped with the kitemark on the faceplate to prove it. It’s the standard most UK home insurers specify for external doors, which is why it’s commonly called an insurance-approved lock. A mobile locksmith covering Bayswater and neighbouring W2 districts fits and checks BS3621 locks to that standard, confirming the price before any work starts.

Mortice deadlocks and nightlatches

BS3621 covers two common lock types. A mortice deadlock sits inside the door edge and is operated by a key from both sides, giving strong resistance when the door is fully locked. It’s the standard fitting for most solid timber front and back doors. A BS3621 nightlatch is surface-mounted with a separate cylinder, useful where the door is too thin for a mortice case.

Some are designed to pair with a mortice deadlock, too, for a two-lock final exit door setup that many insurers prefer. Which is right depends on the door itself: its thickness, existing cut-outs, and whether a deadbolt function is wanted alongside a self-latching action. That’s confirmed on inspection, rather than guessed from a phone call.

Why London flats specifically need this checked

Many London flats and period conversions have had their locks changed multiple times by different tenants, landlords or previous owners over the years. It’s common to find a lock that looks the part but carries no kitemark stamp at all. A BS3621 stamp is the only reliable way to confirm the standard — appearance and price are not proof.

Checking the faceplate on the edge of the door, with it open, takes a minute and settles the question either way. This is worth doing at move-in, at a tenancy changeover, or when reviewing a policy renewal, since it’s a common gap even in well-kept flats.

Fitting and checking service

The service covers checking an existing lock against the standard, and supplying and fitting a new BS3621 mortice deadlock or nightlatch where an upgrade is needed. This is also the natural moment to consider an anti-snap euro cylinder if the door in question is uPVC or composite rather than timber. BS3621 itself applies to mortice and nightlatch locks rather than euro cylinders, so the two are checked separately. For a full lock swap that includes this upgrade, see the lock change page.

After a break-in or a failed lock

A break-in or a lock that has failed outright is a natural point to check the standard. A like-for-like replacement of a non-BS3621 lock can leave a policy technically unmet even after the door is secure again. The burglary repair page covers same-day security after a forced entry, including this check.

Check or upgrade your lock

To find out whether your current lock meets BS3621, or to have an insurance-approved lock fitted, get in touch. request a call back or send the details through the contact form, and a mobile locksmith covering Bayswater and neighbouring W2 districts will confirm what’s needed and the price before any work starts.

Common questions

What is BS3621 and how do I know if my lock is BS3621?

BS3621 is a British Standard for thief-resistant locks, covering how well a mortice lock or nightlatch resists picking, drilling and forcing. A genuine BS3621 lock is stamped with the kitemark and the standard number on the faceplate, usually visible on the edge of the door when it is open — if there is no stamp, the lock has not been tested to the standard, whatever the box or seller claimed.

What does BS3621 mean on a lock?

It means the lock has been independently tested against a British Standard for resistance to picking, drilling and physical attack, and is stamped to show it passed. It's the standard most UK home insurers specify for external doors, so a BS3621 lock is often called an insurance-approved lock.

Is my current lock insurance approved?

Check the faceplate on the edge of the door for a BS3621 kitemark stamp; if it isn't stamped, it is unlikely to meet the standard regardless of how it looks or feels. Your policy document or insurer will confirm exactly what standard they require, since some ask for BS3621 specifically and others accept an equivalent.

Do I need a BS3621 lock on every door, or just the front door?

Most UK home insurance policies focus the requirement on final exit doors — typically the front and back door — rather than every internal or communal door. Check your specific policy wording, since requirements do vary between insurers.

Can a BS3621 lock be fitted to any door?

A BS3621 mortice deadlock needs a door thick enough to house the lock case, which most solid timber doors are, while thinner or hollow doors may need a different approach such as a BS3621 nightlatch instead. A locksmith can check the door on site and recommend the right option before quoting.