Does my home insurance require a BS3621 lock?

Most UK home insurers make a BS 3621 certified lock on external doors a condition of the policy. If your lock does not meet the standard and you suffer a break-in, the insurer can reduce or refuse the claim, even if the lock itself was not the point of failure. Always check your policy wording: for uPVC and composite doors, insurers normally accept a TS 007 3-star or Sold Secure SS 312 Diamond euro cylinder instead. The current version of the standard is BS 3621:2017+A1:2024, but older versions are generally still accepted.

What is the difference between BS3621 and TS007?

BS 3621, currently BS 3621:2017+A1:2024, is the British Standard for mortice deadlocks and rim nightlatches on timber doors that lock with a key from both sides. It requires at least five levers, a hardened anti-drill plate, and a bolt throw of at least 20 mm. Two sister standards cover the same locks with different egress: BS 8621 for keyless egress (thumb-turn inside) and BS 10621 for dual mode. TS 007 is the Door and Hardware Federation specification for euro profile cylinders, the type fitted to most uPVC and composite doors, and a TS 007 3-star cylinder is tested against snapping, picking, drilling, bumping and plug extraction.

What does TS007 3-star mean?

TS 007 3-star is the highest rating within the standard, currently published as DHF TS 007-1:2014+A2:2018. A 3-star cylinder is independently tested to resist five methods of forced entry: drilling, picking, bumping, snapping and plug extraction. It can be fitted on its own without additional door hardware, unlike a 1-star cylinder, which must be combined with TS 007 2-star handles to reach the overall 3-star total. There is also a Part 2 of the standard, DHF TS 007-2:2019, covering mechatronic (electronic) cylinders.

What is anti-snap protection and why does it matter?

Lock snapping is a well-documented attack against uPVC and composite doors in the UK. A burglar grips the exposed part of a standard euro cylinder with basic hand tools and snaps it, exposing the cam and allowing the door to open - it takes seconds and needs no skill. Because every hook and bolt in a multipoint door is driven by that one cylinder, defeating it defeats the whole door. An anti-snap cylinder has a sacrificial break point that separates cleanly under attack, leaving the locking mechanism inside the door intact and the door secured.

What is a Sold Secure Diamond rating?

Sold Secure is an independent UK testing body that rates security products from Bronze up to Diamond, with Diamond the highest grade. For euro cylinders the relevant test is SS 312 Diamond, which applies the scope of the TS 007 3-star test with extra attack time and more aggressive methods, carried out by an experienced locksmith. It is widely treated as equivalent to a Kitemarked TS 007 3-star cylinder and is listed by Secured by Design alongside TS 007 for replacement cylinders. Sold Secure publishes a searchable list of approved products on its own site.

Do I need a high-security lock if I rent my home?

Yes, if you are responsible for contents insurance. Most contents policies reference the same BS 3621 or TS 007 3-star requirement as buildings policies. Check your tenancy agreement before changing any lock, and ask the landlord to upgrade if the existing locks fall short - especially on uPVC doors, where an unrated snappable cylinder is common. If your front door is on a shared escape route, the correct specification is usually BS 8621 (thumb-turn inside) rather than BS 3621, so you are never locked in.

Is there a security standard for smart locks in the UK?

Yes. DHF TS 621:2018 is the UK standard for complete electronic door locking devices. It tests attack resistance, credential security and the vulnerability of the radio network, and it requires an interior mechanical override so a power failure cannot trap you inside. Mechatronic cylinders are covered separately by DHF TS 007-2:2019. On the digital side, the BSI IoT Kitemark and the Smart Residential Locking Device Kitemark cover firmware, encryption and update security. See our guide to smart locks for UK homes for which products carry what.

How much does it cost to upgrade to a high-security lock in London?

City Locksmith London charges from £69 for lock change labour and from £89 per hour for a fresh lock installation (prices ex VAT). The cost of the high-security cylinder or lock itself is additional and varies by brand. We provide free quotes so you know the full price before any work begins.

What Are High-Security Locks and When Do You Need Them?

A high-security lock is one that has been independently tested and certified against a published standard for picking, drilling, bumping, snapping and plug extraction - not simply one marketed as “high security”. In the UK the two that matter for a front door are BS 3621:2017+A1:2024 for mortice deadlocks and rim nightlatches on timber doors, and TS 007 3-star (or the equivalent Sold Secure SS 312 Diamond) for euro profile cylinders on uPVC and composite doors. Most UK home insurance policies make one of these a condition of cover, and a lock that falls short can cost you a claim even when nothing failed. City Locksmith London fits certified cylinders and mortice locks across all London postcodes from £69 labour for a lock change and from £89 per hour for a fresh installation (ex VAT), with a free quote before any work starts.

What Makes a Lock “High Security”?

Not all locks labelled “high security” are independently certified. The meaningful distinction is whether a lock has been tested against a published British or industry standard and carries the relevant mark - the BSI Kitemark, Secured by Design, or Sold Secure.

In practical terms, a high-security lock differs from a standard lock across five areas:

1. Hardened Materials

High-security locks use hardened steel components throughout the mechanism. This resists drilling - a common forced-entry technique - and extends the working life of the lock.

2. Advanced Internal Mechanisms

Standard pin tumbler locks use a relatively simple arrangement of spring-loaded pins. High-security equivalents add sidebars, anti-pick pins, spool pins, and other features that make manipulation significantly harder. These mechanisms cannot be defeated by the bump key or basic picking techniques that open standard locks.

3. Key Control

Many high-security locks use patented key blanks that can only be duplicated by authorised dealers with proof of ownership. Even if someone obtains your key, they cannot copy it at a high-street kiosk.

4. Anti-Drilling Protection

Hardened steel pins or anti-drill plates are positioned at critical points within the lock body. When a drill bit strikes these components, it deflects rather than biting.

5. Anti-Snap Design

Euro cylinders fitted to uPVC and composite doors are particularly vulnerable to snapping. High-security cylinders include a sacrificial break point that separates when attacked, leaving the internal cam - and your door - secure.

Which UK Lock Standards Should You Look For?

Understanding the certification labels helps you choose the right lock and satisfy your insurer.

Standard	Applies To	What It Tests	Key Benefit
BS 3621:2017+A1:2024	Mortice deadlocks, rim nightlatches on timber doors - key operated from both sides	Picking, drilling, sawing, key-bumping; min. 5 levers, 20 mm bolt throw	The specification most UK home insurers name for a final exit door
BS 8621:2017+A1:2024	The same locks, but with keyless egress - key outside, thumb-turn inside	As BS 3621	The correct choice where escape without a key matters (flats, HMOs, rooms on an escape route)
BS 10621:2017+A1:2024	Dual-mode: thumb-turn inside plus the ability to deadlock from outside	As BS 3621	Only for properties with an alternative means of escape
DHF TS 007-1:2014+A2:2018, 1-star	Euro cylinders (uPVC/composite doors)	Drilling, picking, bumping - but NOT snapping	Must be combined with 2-star handles to reach the 3-star total
DHF TS 007-1:2014+A2:2018, 3-star	Euro cylinders	Snapping, drilling, picking, bumping, plug extraction	Highest cylinder rating; accepted stand-alone, no special handle needed
DHF TS 007-2:2019	Mechatronic cylinders (electronic cylinder driving a mechanical case)	As above, adapted for electronic cylinders	The route to certification for electronic cylinder upgrades
DHF TS 621:2018	Complete electronic (mechatronic) lock assemblies and smart locks	Attack resistance, credential security, radio-network vulnerability, mandatory interior mechanical override	The only UK physical-security standard written for smart locks
Sold Secure SS 312 Diamond	Euro cylinders	TS 007 3-star scope applied with added attack time and aggression, tested by an experienced locksmith	Widely treated as the equivalent of a Kitemarked 3-star cylinder
Sold Secure Gold/Diamond	Padlocks	Progressive attack resistance; Diamond = specialist tools	Used for gates, outbuildings, vehicle security
PAS 24	Complete new door and window assemblies	Whole-doorset security testing	Referenced by Part Q of the Building Regulations for new dwellings
Secured by Design	Doors, windows, hardware, connected devices	Police-owned specification scheme drawing on the standards above	Police Preferred Specification; recognised by some insurers

Secured by Design, the police-owned security initiative, sets the division out plainly in its locks and hardware guidance: replacement locks fall under BS 3621, BS 8621 and BS 10621; replacement cylinders under DHF TS 007 and Sold Secure SS 312 Diamond; new door assemblies under PAS 24; and complete mechatronic lock assemblies under DHF TS 621.

Quick rule: For a timber front door, open the door and look for the BSI Kitemark and “BS 3621” stamped on the lock faceplate. For a uPVC or composite door, look for the Kitemark and “TS 007 3-star” on the cylinder end cap, or the Sold Secure Diamond mark.

Does Home Insurance Require Specific Locks?

Yes - this is one of the most misunderstood areas of home security. Most UK home insurers include a locks clause in their policy conditions that specifies:

All external ground-floor doors must be fitted with a BS3621 mortice deadlock or equivalent.
For uPVC and composite doors, a TS007 3-star cylinder or equivalent (such as Sold Secure SS312 Diamond) is typically accepted.
Patio and French doors are usually required to have multi-point locking.

If your locks do not meet the required standard and you suffer a break-in, your insurer can reduce or refuse your claim - even if nothing was technically wrong with the lock when the break-in occurred.

Some insurers also offer a premium discount for locks that exceed the minimum standard - for example, Secured by Design certification or electronic access control on commercial properties.

Always check your specific policy wording. The current version of the standard is BS 3621:2017+A1:2024, but older BS 3621 versions are generally still accepted.

One thing worth being straight about: burglary in England and Wales is falling. ONS figures for the year ending March 2026, published on 23 July 2026, show police recorded burglary (residential and non-residential combined) down 9% to 223,456 offences. That is genuinely good news, and it does not change your insurance position by a penny. The locks clause is a contractual condition, not a risk assessment - if the policy says BS 3621 or a 3-star cylinder and your door does not have one, the insurer can still reduce or refuse a claim.

What Types of High-Security Lock Are There?

High-Security Mortice Deadlocks

The traditional choice for timber front and back doors. A BS3621 five-lever mortice deadlock is the standard requirement. Brands such as Yale, Banham, Ingersoll, and ERA manufacture Kitemarked versions at a range of price points.

For higher-risk properties, cylinder mortice deadlocks from Abloy or Mul-T-Lock add patented key control on top of the BS3621 base certification.

TS007 3-Star Euro Cylinders

The most important upgrade for the majority of London homes with uPVC or composite doors. A standard euro cylinder can be snapped in seconds with basic hand tools bought from any DIY shop, and because every hook and bolt in a multipoint door is driven by that one cylinder, defeating it defeats the whole door. A TS 007 3-star replacement cylinder is a direct swap with no door modification, and adds anti-snap, anti-pick, anti-drill and anti-bump protection.

Two fitting details decide whether it actually works. The cylinder must be the right length so it sits flush with or just inside the handle - a cylinder protruding past the furniture gives an attacker something to grip. And if you are using a 1-star cylinder rather than a 3-star one, it only reaches the 3-star total when paired with TS 007 2-star security handles. Our uPVC locksmith services cover cylinder measuring, supply and fitting on multipoint doors.

Our guide to replacing a barrel lock in a uPVC door explains how cylinders work and what to look for when choosing a replacement.

For a broader comparison of lock types and security ratings, see our guide on the best front door locks for UK homes.

High-Security Padlocks

Closed-shackle design - which exposes far less of the shackle to bolt-cutters - combined with a Sold Secure Gold or Diamond cylinder makes for a highly resistant padlock. Suitable for gates, outbuildings, garage side doors, and storage units. Look for a CEN4 rating or above alongside the Sold Secure grade.

Electronic and Smart Locks

High-security electronic locks combine physical resistance with digital access control. Codes can be changed instantly, audit logs record every entry, and biometric models ensure only enrolled users can gain access. These are increasingly common in commercial environments and some residential properties. See our guide to smart locks for UK homes for current options.

When Do You Need High-Security Locks?

Your Home Insurance Requires It

As covered above, BS3621 and TS007 3-star are standard insurance conditions. If you are not sure whether your current locks comply, a lock change assessment from a qualified locksmith will clarify the position quickly.

After a Break-In

A break-in - whether or not entry was forced - is the right moment to reassess your entire door security, not just replace the damaged component. Our break-in repair service includes a security audit as standard.

Your Door Has a Standard Euro Cylinder

If your uPVC or composite door has a cylinder with no TS 007 star rating and no Sold Secure mark, assume it is snappable. It is the cheapest weakness on the door and the cheapest one to remove - an anti-snap cylinder swap is labour from £69 plus the cylinder, and needs no change to the door itself.

You Own a Second Property or Holiday Let

Properties that stand empty for extended periods are disproportionately targeted. High-security locks combined with a monitored alarm significantly reduce risk.

You Hold High-Value or Sensitive Contents

Art, jewellery, specialist equipment, and confidential records all increase the cost-benefit ratio of investing in certified hardware. Insurers may also specify higher standards for contents policies covering items above certain values.

Commercial and Business Premises

Businesses have additional drivers beyond personal security:

Retail and hospitality with high-value stock or cash on site
Professional services (law firms, accountants, medical practices) with confidential client data
Warehousing and logistics where stock values are significant
Server rooms and data centres where physical access control is a regulatory requirement under ISO 27001 or similar frameworks

A door lock installation on commercial premises should include a review of masterkey systems, access levels, and audit logging requirements alongside the hardware specification.

What Should You Check Before Buying a High-Security Lock?

Check the Kitemark - the BSI Kitemark on a lock confirms independent third-party testing, not just a manufacturer claim.
Match the standard to your door type - BS3621 for timber mortice locks; TS007 3-star for euro cylinders.
Measure the cylinder correctly - a euro cylinder fitted too long is still snappable at the protruding end. Measure the cylinder so it sits flush with or just inside the door furniture.
Consider key control - if key management matters (rented property, shared access), a patented key profile adds meaningful security.
Check your insurer’s wording - some policies name specific standards; others accept equivalents. When in doubt, call your insurer before purchasing.

Our lock price list sets out the current rates for supply and installation, including high-security cylinders and mortice locks. Lock change labour starts from £69; fresh installations from £89 per hour (prices ex VAT, no call-out fee, free quotes).

Do You Need a Locksmith to Fit a High-Security Lock?

The correct specification matters as much as the quality of the hardware. The wrong cylinder length, an insufficiently deep mortice pocket, or a misaligned strike plate can undermine even the best lock. City Locksmith London has been fitting high-security locks across Greater London for over 15 years, with fully insured and DBS-checked engineers.

Iulian H., lead locksmith at City Locksmith London, says: “Most doors we upgrade do not need a new lock case at all - they need the right cylinder, cut to the right length, with the strike plate reset. We measure, tell you the full price, and only then fit.

For a comparison of all lock and window security types we work with, see our guide to door and window lock types.

To discuss the right specification for your property, contact us directly for a free assessment. We respond within 25 minutes, 24 hours a day, across all London postcodes.