Insurance approved lock checker

Describe each external door and the markings you can see on its locks to find out whether it is likely to meet the common insurer wording, and what to look for if it does not. Based on Master Locksmiths Association, DHF, Secured by Design and Sold Secure guidance, checked 9 November 2026. Your insurer's own policy wording is what counts.

How the lock checker works

Home insurance applications ask what locks are fitted to the external doors, and policies often set a minimum. The most common wording asks for a five lever mortice deadlock to BS 3621, or a multipoint locking system with a TS 007 3 star or Sold Secure Diamond cylinder, or something equivalent. The checker takes the door material, the lock type and the markings you can see, and tells you whether that door is likely to meet the wording, unlikely to, or needs a closer look. It then lists where on the door to find the marks that would settle it.

A worked example: a timber front door with a Yale type nightlatch and a mortice deadlock whose faceplate shows the Kitemark and BS 3621. That is exactly the pairing the Master Locksmiths Association describes, so the door is likely to meet the wording. A uPVC back door with a multipoint lock and a plain euro cylinder with no markings is listed as needing a check, because the cylinder is the weak point and the MLA says unrated euro cylinders are prone to lock snapping. Tick the TS 007 3 star box for that cylinder and the door becomes likely to meet the wording.

The standards explained

BS 3621, BS 8621 and BS 10621

BS 3621 is the British Standards Institution's standard for thief resistant locks that need a key from both sides. Secured by Design calls it the minimum standard for locks on external doors. The MLA says a BS 3621 mortice lock has at least five levers, though some five lever locks are not certified, and that a genuine one carries the Kitemark and the standard number on its faceplate. BS 8621 is the keyless exit version, opened from inside by a thumb turn or handle, and BS 10621 can switch between the two; the MLA warns that BS 10621 should not be used in homes with a single exit. The current editions are the 2017 versions with the 2024 amendment.

TS 007 and the star ratings

TS 007 is the Door and Hardware Federation's specification for replacement euro cylinders and the handles that protect them, developed with Secured by Design and the Glass and Glazing Federation. The DHF says the cylinder must withstand five types of attack. There are two ways to reach full protection: a TS 007 Kitemarked 3 star cylinder on its own, or a Kitemarked 1 star cylinder combined with a 2 star Kitemarked armoured handle or lock surround. The marks are on the end of the cylinder and on the handle backplate.

Sold Secure Diamond and Gold

Sold Secure, owned by the Master Locksmiths Association, tests cylinders to its SS312 specification. Its guide says the Diamond grade can be used on its own and is equivalent to TS 007 3 star, while the Gold grade is equivalent to 1 star and must be paired with an SS301 handle or escutcheon. The DHF confirms that Diamond cylinders achieve the same level of protection and are police approved under Secured by Design.

PAS 24 doors and PAS 3621 multipoint locks

A complete door set tested to PAS 24 and supplied with a Secured by Design certificate has, in the MLA's words, been tested to a very high level of attack. Secured by Design also lists PAS 3621, PAS 8621 and PAS 10621 as the multipoint lock equivalents of the three British Standards. A PAS 24 certificate covers the door as sold, so if the cylinder has since been replaced, check its rating separately.

Where to look for the markings

Mortice deadlock or sashlock: open the door and read the faceplate on the door edge. The Kitemark and BS number are stamped or engraved there.
Nightlatch: the marks are on the latch case on the inside face of the door, sometimes under the handle.
Euro cylinder: look at the brass or chrome end where the key goes in. A Kitemark with one or three stars, or a Sold Secure Diamond mark, sits on the face or the side.
Security handles: a 2 star Kitemark is usually on the backplate of the handle, sometimes visible only with the handle removed.
Paperwork: a PAS 24 or Secured by Design certificate came with the door when it was fitted, and the fitter's invoice may name the cylinder.

Common mistakes and tips

Counting levers instead of reading the faceplate. Five levers is the minimum for BS 3621, but it does not make a lock certified.
Trusting the door, not the cylinder. On uPVC and composite doors the cylinder decides whether the common wording is met.
Relying on a nightlatch alone. The MLA says it needs a BS 3621 deadlock alongside it unless the nightlatch is itself BS 3621.
Forgetting the back and side doors. Policies apply to all external doors, and patio and French doors count.
Not locking the locks. The MLA notes that if the locking system is not used properly, the insurer may not pay out.

When to get a professional

A locksmith can identify an unmarked lock, confirm whether a cylinder is rated, and fit a BS 3621 deadlock or a TS 007 3 star cylinder in an hour or so. Upgrading a cylinder is one of the cheapest security improvements there is. Ask for a receipt that names the standard, because insurers sometimes ask for proof after a claim. Choose a locksmith who is vetted, inspected and qualified, and get a written quote before work starts.

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How this is worked out

Mortice deadlock or sashlock: likely if marked BS 3621; check if marked BS 8621, BS 10621 or Kitemark only; unlikely if "5 lever" without a Kitemark or unmarked.
Multipoint lock: likely if the cylinder is TS 007 3 star or Sold Secure Diamond, or a 1 star or Gold cylinder is paired with 2 star handles, or the door has a PAS 24 or Secured by Design certificate; unlikely if the cylinder is 1 star or Gold alone; check if PAS 3621 only or unmarked.
Nightlatch only: likely if the nightlatch is BS 3621; check if BS 8621; otherwise unlikely.
Nightlatch plus mortice deadlock: likely if the deadlock is BS 3621; check if BS 8621 or BS 10621, or if only a Kitemark or lever count is visible; otherwise unlikely.

Master Locksmiths Association, What are BS3621 locks and how to tell you have British Standard locks (checked 9 November 2026). BS 3621 is the BSI standard for thief resistant locks; a BS 3621 mortice lock has at least 5 levers, and some 5 lever locks do not conform; look for the Kitemark and the standard number on the faceplate; the current version is BS 3621:2017+A1:2024; "some insurance companies require door locks are fitted to BS 3621" but the locks are certified by BSI, not approved by insurers; BS 8621 is for keyless exit and BS 10621 is dual mode and should not be used in single exit dwellings.
Master Locksmiths Association, Night latches: a simple guide (checked 9 November 2026). A nightlatch is "only truly secure if it is BS3621 Approved OR is fitted alongside a 5 lever Mortice Deadlock that conforms to BS3621"; standard latches "require a secondary lock to meet insurance requirements (like a BS3621 deadlock)"; approved locks are sometimes a requirement of home insurance providers.
Master Locksmiths Association, Door lock types: a simple guide for your home (checked 9 November 2026). Euro cylinders are prone to lock snapping; fit a cylinder that is Sold Secure SS312 Diamond or TS 007 3 star; a 1 star cylinder should be paired with 2 star handles; a composite door tested to PAS 24 with a Secured by Design certificate has been tested to a very high level of attack; a non-BS3621 five lever deadlock may only be tested by the manufacturer; a non-tested nightlatch must be supported by a tested lock.
Door and Hardware Federation (DHF), TS 007 (checked 9 November 2026). The lock cylinder needs to withstand five types of attack; fit "a TS 007 Kitemarked 3-Star cylinder" or "a TS 007 Kitemarked 1-star cylinder combined with a TS 007 2-star Kitemarked armoured handle or lock surround"; cylinders meeting the MLA's Sold Secure Diamond (SS312) standard "will also achieve this level of protection and are Secured by Design (police) approved". TS 007 was developed by Secured by Design, DHF and the Glass and Glazing Federation.
Secured by Design, Standards explained: locks and associated hardware (checked 9 November 2026). BS 3621:2017+A1:2024 (key both sides) is "the minimum standard for locks on external or entrance doors"; BS 8621 is keyless egress; BS 10621 is dual mode, only for properties with an alternative means of escape; PAS 3621:2011, PAS 8621:2011 and PAS 10621:2011 are the multipoint lock equivalents; DHF TS 007:2014+A2:2018 covers replacement cylinders and hardware; Sold Secure SS312 Diamond is a specification for lock cylinders.
Sold Secure, Domestic Security grades (PDF) (February 2024, checked 9 November 2026). SS312 Diamond cylinders can achieve the required security as a standalone cylinder and the grade "is equivalent to TS007 3 Star"; SS312 Gold "is equivalent to TS007 1 Star" and must be coupled with an SS301 handle or escutcheon; insurance companies often recommend Sold Secure approved products.

Related guides

Lock standard questions

What locks do insurers usually ask for?

The wording varies, but the common version asks for a five lever mortice deadlock to BS 3621 on timber doors, or a multipoint locking system with a TS 007 3 star (or Sold Secure Diamond) cylinder on uPVC and composite doors, or equivalent. The Master Locksmiths Association notes that some insurers require BS 3621 and others do not, and that the locks are certified by BSI rather than approved by insurers. Your own policy wording is what counts.

How do I know if my lock is BS 3621?

Open the door and look at the faceplate, the metal strip on the edge of the door around the bolt. The MLA says a BS 3621 lock carries the BSI Kitemark and the standard number there, for example BS 3621:2017. A nightlatch shows the marks on its case inside the door. Five levers alone is not enough: the MLA says some five lever locks do not conform.

Is my uPVC door lock insurance approved?

Look at the end of the euro cylinder where the key goes in. A TS 007 Kitemark with three stars, or a Sold Secure Diamond mark, is what the common wording asks for. A one star cylinder counts when it is fitted with two star Kitemarked security handles, according to the DHF. If there are no marks, the cylinder is probably a standard one and the MLA warns these are prone to snapping.

Is Sold Secure Diamond the same as TS 007 3 star?

Sold Secure's own guide says its SS312 Diamond cylinder grade is equivalent to TS 007 3 star, and the DHF says Diamond cylinders achieve the same level of protection and are police approved under Secured by Design. Most insurer wording that names TS 007 3 star also accepts Sold Secure Diamond, but check the policy if it names only one.

Is a Yale nightlatch enough on its own?

Not usually. The MLA says a nightlatch is only truly secure if it is itself BS 3621 approved or is fitted alongside a BS 3621 five lever mortice deadlock, and that standard latches need a secondary lock to meet insurance requirements. A door with just a standard nightlatch is a common reason for a claim to be questioned.

What about BS 8621 and BS 10621 locks?

They are the same family of thief resistant lock. BS 8621 opens from inside without a key, which suits flats and homes where fire escape matters, and BS 10621 can be switched between the two modes. Secured by Design lists all three, but many policies quote only BS 3621, so ask the insurer whether the alternative is accepted before relying on it.

Locks that do not meet your policy? Compare well reviewed locksmiths near you for a BS 3621 deadlock or a 3 star cylinder.