Understanding lock grades in the UK can help homeowners choose suitable door security, identify outdated locks and check whether their property meets the requirements of their home insurance policy.
However, terms such as British Standard locks, BS3621, insurance-approved locks, TS007, Sold Secure and three-star anti-snap cylinders are often used interchangeably. They do not mean the same thing.
Different standards apply to different locking products. BS3621 is commonly associated with thief-resistant locks on timber doors, while TS007 covers enhanced security requirements for replacement cylinders and protective hardware. Sold Secure independently tests various security products, and European standards cover everything from complete doorsets to safes and strongrooms.
For homeowners, the most important question is straightforward: Does the lock fitted to your door meet the security requirements stated in your home insurance policy?
In this guide, Sam from AHLP Locksmiths explains the main UK lock standards, what their ratings mean, how BS3621 relates to home insurance and how to check the locks already fitted to your property.
UK Lock Grades and Security Standards at a Glance
There is no single grading system covering every type of door lock in the UK.
Instead, different standards assess different products and security features. Some focus on complete lock assemblies, while others assess replacement cylinders, protective hardware or the resistance of an entire door.
Understanding lock grades UK homeowners commonly encounter can help you decide whether your existing locks provide suitable protection or whether professional lock changing and security upgrades may be appropriate.
The table below explains the main standards homeowners may encounter.
Standard or certification | What it covers | Common application |
|---|---|---|
BS3621 | Thief-resistant lock assemblies operated by key from both sides | Timber entrance doors |
BS8621 | Thief-resistant lock assemblies allowing keyless escape from inside | Doors requiring convenient emergency exit |
BS10621 | Thief-resistant lock assemblies with dual-mode operation | Doors requiring selectable locking arrangements |
TS007 | Enhanced security for replacement cylinders and protective hardware | uPVC and composite doors |
Sold Secure SS312 | Independent security testing of lock cylinders | Enhanced cylinder protection |
BS EN 1627 | Burglar resistance of complete doorsets, windows and related products | Security-rated doors and windows |
BS EN 1143-1 | Burglary resistance of safes and strongrooms | Secure storage of valuables |
These standards are not interchangeable. A TS007 three-star cylinder cannot be directly compared with a BS3621 mortice lock because the standards assess different products.
The appropriate standard depends on your door type, locking arrangement and any specific insurance requirements.
What Is a British Standard Lock?
A British Standard lock is a lock that meets the requirements of a particular British Standard published by the British Standards Institution (BSI).
It is not one universal security grade covering every type of lock.
For domestic entrance doors, BS3621 is one of the most frequently referenced standards, particularly for qualifying locks fitted to timber doors.
Other standards, including BS8621 and BS10621, apply to locking arrangements with different operating and escape requirements.
For many uPVC and composite doors using Euro cylinders, TS007 is more relevant when assessing cylinder security and the surrounding protective hardware.
The important point is to match the standard to the type of door and locking system rather than simply looking for the words “British Standard” on the packaging.
BS3621: Thief-Resistant Locks and Home Insurance Requirements
BS3621 is a British Standard covering thief-resistant lock assemblies with key operation from both sides.
You are most likely to encounter it on locks fitted to timber entrance doors, including qualifying mortice deadlocks, sashlocks and certain night latches.
Products certified to BS3621 must meet specified requirements for construction, operation and resistance to attack.
Is BS3621 the same as a five-lever mortice lock?
Not exactly.
Five-lever mortice deadlocks are commonly associated with BS3621, but having five levers does not automatically mean a lock meets the standard.
A five-lever lock without the appropriate certification may not satisfy an insurance policy specifically requiring BS3621.
Likewise, BS3621 is not limited exclusively to five-lever mortice deadlocks. Other qualifying lock assemblies can also be certified.
The distinction is between the mechanical design of a lock and its compliance with an independently assessed standard.
How do I know if my lock is BS3621?
Open the door and inspect the metal forend or faceplate along the edge of the door, where the lock bolt and latch emerge.
On a BSI-certified lock, look for:
The BSI Kitemark.
The standard number BS3621.
The relevant version or year of the standard, where shown.
Manufacturer or product identification.
The Kitemark indicates independent BSI certification rather than simply a manufacturer’s statement that the product meets the standard.
If the markings have been painted over, are difficult to read or cannot be located, do not automatically assume that the lock is unsuitable.
Identify the manufacturer and model or ask a locksmith to check the certification before replacing an otherwise functional lock.
BS3621 Insurance Requirements: Does Your Home Need These Locks?
One of the most common questions about home security is whether UK home insurance requires BS3621 locks.
There is no universal requirement for every UK homeowner to install BS3621 locks.
Some insurance policies specifically require BS3621-certified locks on certain external doors, particularly timber entrance doors. Others describe acceptable locking arrangements differently.
For example, a policy may refer to:
A five-lever mortice deadlock conforming to BS3621.
A suitable multipoint locking system on a uPVC or composite door.
Key-operated locks on accessible windows.
Particular security requirements for patio or sliding doors.
Additional locking conditions when the property is unoccupied.
The exact requirements depend on the insurer, policy wording and property.
If you are reviewing BS3621 insurance requirements, it is important to identify the type of lock fitted to your door before arranging a replacement. For uPVC and composite doors, upgrading the Euro cylinder may be appropriate where the existing cylinder does not meet the required security specification. However, a cylinder replacement is not a substitute for a BS3621-certified lock where that specific standard is required.
Does a BS3621 lock guarantee home insurance cover?
No.
A BS3621-certified lock may satisfy a particular security requirement, but it does not guarantee that every condition of your insurance policy has been met.
Insurers may also specify requirements for other doors, windows, alarms or how security devices must be used when the property is unattended.
Always check your policy schedule, security endorsements and conditions of cover.
Can an insurer reject a burglary claim because of the wrong locks?
Failing to meet an applicable security condition can create difficulties when making a claim.
However, whether an insurer can decline a particular claim depends on the policy wording, the circumstances and applicable insurance law.
It would be misleading to suggest that every burglary claim is automatically refused because a lock lacks a particular certification.
If you are unsure whether your current locking arrangement meets the policy conditions, ask your insurer or broker to confirm the requirements in writing.
BS8621 and BS10621: Other British Lock Standards Explained
BS3621 is not the only British Standard covering thief-resistant door locks.
Two additional standards are worth understanding, particularly when considering how occupants can unlock a door from inside.
BS8621: Keyless escape from inside
BS8621 covers thief-resistant lock assemblies designed to allow keyless escape from inside.
Unlike a BS3621 arrangement requiring a key for operation from both sides, a qualifying BS8621 lock allows the occupant to unlock the door internally without using a key.
This distinction can be important where convenient emergency escape is necessary.
However, suitability depends on the door, property requirements and applicable insurance conditions.
BS10621: Dual-mode locking arrangements
BS10621 covers thief-resistant lock assemblies incorporating dual-mode operation.
These locks provide different operating modes, including arrangements for keyless escape and more restrictive locking.
Because the selected mode affects how the door operates, suitability should be considered carefully where emergency escape requirements apply.
Neither BS8621 nor BS10621 should automatically be treated as interchangeable with BS3621 for insurance purposes.
The insurer’s actual wording remains important.
TS007: Understanding One-Star, Two-Star and Three-Star Lock Ratings
TS007 covers enhanced security requirements for replacement cylinders and associated protective hardware.
It is particularly relevant to Euro cylinder locks commonly used with multipoint locking systems on uPVC and composite doors.
The star-rating system is designed to identify different levels and combinations of cylinder and protective hardware security.
However, a two-star rating is not simply a middle-grade cylinder.
TS007 one-star cylinders
A one-star cylinder meets the relevant requirements of the specification.
However, a one-star cylinder alone does not provide the complete three-star security arrangement.
It can be combined with suitable two-star protective hardware to achieve the recognised cumulative three-star configuration.
TS007 two-star protective hardware
A two-star rating applies to security hardware, such as an appropriate protective handle or escutcheon.
It is not a separate two-star cylinder grade.
The hardware is designed to provide additional protection around the cylinder against specified forms of attack.
TS007 three-star cylinders
A three-star cylinder achieves the required three-star security level without relying on separate two-star protective hardware for that rating.
These cylinders are commonly discussed in connection with anti-snap security because they are designed to resist specified cylinder attacks.
The recognised arrangements are:
Lock cylinder and hardware | Combined TS007 rating |
|---|---|
One-star cylinder + two-star protective hardware | Three stars |
Three-star cylinder | Three stars without additional two-star hardware being required for that rating |
Both arrangements can achieve the recognised three-star configuration when the products are correctly certified and installed.
For more information about cylinder protection, read our guide to the advantages of anti-snap locks.
What Are Anti-Snap Locks and Why Are They Important?
Lock snapping is a method of forced entry that targets vulnerable Euro profile cylinders.
When a poorly protected cylinder is attacked and broken, the internal locking mechanism may become accessible.
Anti-snap cylinders incorporate design features intended to resist this form of attack and protect the locking mechanism.
Depending on the product, these may include sacrificial sections, reinforced components and other protective features.
However, not every cylinder advertised as “anti-snap” carries the same independent certification.
What should you look for in an anti-snap cylinder?
When choosing a replacement, consider:
Verifiable TS007 three-star certification.
Relevant Sold Secure approval, where applicable.
Correct cylinder sizing for the door.
Compatibility with the existing locking mechanism.
Suitable protective handles or escutcheons.
Proper installation without excessive cylinder projection.
A high-security cylinder must be correctly fitted to provide its intended protection.
If the existing multipoint locking mechanism works properly, replacing the cylinder may be sufficient without changing the entire mechanism.
Sold Secure: Independent Security Testing and Lock Grades
Sold Secure is an independent security testing and certification organisation established in 1992.
Its testing covers a wide range of products, including:
Lock cylinders.
Domestic building security products.
Garage door security.
Padlocks and fittings.
Key safes.
Multipoint locks.
Gate security.
Ground anchors.
Smart locks.
Safes and security cabinets.
Products submitted for approval undergo testing against the relevant specification.
Products that successfully meet the applicable requirements can carry the Sold Secure Approved mark.
What do Sold Secure Bronze, Silver, Gold and Diamond mean?
Sold Secure uses different grading systems depending on the product category and relevant specification.
You may therefore encounter ratings such as Bronze, Silver, Gold and Diamond.
However, these grades should always be understood in the context of the product being assessed.
A Diamond approval for a cylinder is not directly equivalent to a Diamond approval for a different type of security product.
What is Sold Secure SS312 Diamond?
SS312 Diamond is a recognised Sold Secure approval associated with enhanced resistance to attacks against lock cylinders.
It is particularly relevant when comparing cylinders designed to protect against snapping and other specified methods of attack.
However, Sold Secure approval and TS007 certification are separate assessments.
A cylinder may hold one or both certifications.
Neither should automatically be treated as satisfying every home insurance policy.
BS EN 1627: Security Standards for Complete Doors and Windows
BS EN 1627 looks beyond an individual lock.
It establishes requirements and classifications for the burglar resistance of products including:
Pedestrian doorsets.
Windows.
Shutters.
Grilles.
Curtain walling.
The standard uses resistance classes to describe the performance of complete products against specified forms of attack.
These classifications should not be confused with TS007 star ratings or BS3621 lock certification.
A strong cylinder fitted into a weak or damaged door does not automatically make the complete doorset equally resistant to forced entry.
The condition of the door, frame, hinges, handles and locking mechanism matters.
If you are comparing different door constructions, our guide to uPVC vs wooden door locks explains how their locking systems differ in typical UK homes.
BS EN 1143-1: Security Grades for Safes and Strongrooms
BS EN 1143-1 concerns secure storage rather than ordinary domestic door locks.
It establishes requirements, classifications and test methods for the burglary resistance of products including:
Freestanding safes.
Built-in safes.
ATM safes.
Strongroom doors.
Strongrooms.
An EN 1143-1 security grade should not be compared directly with a TS007 star rating or BS3621 certification because they assess different products.
If your home insurance specifies a particular safe grade for jewellery, cash or other valuables, check the exact policy wording and product certification.
A product marketed as a “security safe” does not automatically meet the required standard.
What Does “Insurance-Approved Lock” Actually Mean?
The phrase “insurance-approved lock” is commonly used in security marketing, but it does not identify one universal certification.
A lock is suitable for insurance purposes when it meets the relevant requirements of the individual policy.
For example, a BS3621-certified mortice lock may be appropriate for one timber entrance door, while a multipoint locking arrangement may be accepted on another door.
Similarly, a TS007 three-star cylinder provides enhanced security but is not automatically required by every insurer.
Common UK home insurance lock requirements
Door or security feature | Possible policy requirement | What to check |
|---|---|---|
Timber front door | BS3621-certified mortice lock | Kitemark and standard identification |
Timber back door | Specified mortice lock or approved arrangement | Lock type and policy wording |
uPVC entrance door | Multipoint locking system | Correct engagement and operation |
Composite entrance door | Multipoint lock or another specified arrangement | Mechanism and cylinder requirements |
Euro cylinder | Particular security specification, where required | TS007 or other relevant certification |
Accessible windows | Key-operated window locks | Lock presence and working condition |
Safe for valuables | Specified security grade | Product certification and policy conditions |
These are examples rather than universal insurance requirements.
The safest approach is to compare your existing locks with the wording of your policy before purchasing replacements.
How to Check Whether Your Existing Locks Meet Insurance Requirements
Checking your locks does not necessarily require specialist equipment or immediate replacement.
Start with the insurance documents and work through the following steps.
Step 1: Read your home insurance policy
Look for headings such as:
Security.
Minimum security.
Door and window locks.
Endorsements.
Conditions of cover.
Protections.
Write down the exact lock type or standard specified.
If the policy refers to BS3621, TS007 or another certification, make sure you understand which door or security product the requirement applies to.
Step 2: Identify the type of door
A timber entrance door with a mortice lock requires a different assessment from a uPVC or composite door with a multipoint mechanism and Euro cylinder.
Knowing the door type helps prevent you from looking for the wrong certification.
Step 3: Look for the certification marking
For BS3621 locks, open the door and inspect the metal faceplate or forend.
Look for the BSI Kitemark and BS3621 marking.
For TS007 cylinders or protective hardware, look for the relevant Kitemark and star rating.
Some markings may not be visible while the product is installed.
Avoid dismantling a working lock unnecessarily simply to locate a marking.
Step 4: Check the complete locking arrangement
A multipoint mechanism does not automatically mean the cylinder has enhanced security certification.
Likewise, a high-security cylinder does not prove that the surrounding door, frame and locking mechanism are in good condition.
Check whether the door closes correctly and whether the locking points engage smoothly.
Step 5: Confirm the requirements with your insurer
If you cannot identify the lock or the policy wording is unclear, contact your insurer or broker.
Ask them to confirm what is required for your particular door type.
Where possible, obtain written confirmation.
Step 6: Arrange an appropriate lock upgrade
If the existing hardware does not meet the required specification, a locksmith can assess the door and recommend a suitable replacement.
The solution may involve changing a mortice lock, upgrading a cylinder or repairing an existing locking mechanism.
Where Is the British Standard Kitemark on a Lock?
On many BS3621 mortice locks, the easiest place to check is the metal strip visible on the edge of the door when it is open.
You are looking for the BSI Kitemark together with the relevant standard number.
The markings are commonly stamped or engraved into the hardware rather than printed on a removable label.
For cylinders and protective hardware certified under TS007, look for the Kitemark and relevant star symbols.
What if my lock has no visible Kitemark?
An absent or unreadable marking does not automatically prove that the lock fails to meet the required standard.
The markings may be concealed by paint or located on a part of the product that is not readily visible.
Identify the manufacturer and model before assuming that replacement is necessary.
Where appropriate, product certification can also be checked against the relevant certification directory.
British Standard Locks vs TS007 vs Sold Secure
These terms become easier to understand once you stop treating them as competing grades.
Standard or scheme | Mainly applies to | What to look for |
|---|---|---|
BS3621 | Thief-resistant lock assemblies commonly found on timber doors | BSI Kitemark and BS3621 marking |
BS8621 | Thief-resistant locks with keyless internal escape | Relevant standard and certification |
BS10621 | Thief-resistant locks with dual-mode operation | Relevant standard and certification |
TS007 | Replacement cylinders and associated protective hardware | Kitemark and star rating |
Sold Secure | Independently tested security products | Approval and relevant product grade |
BS EN 1627 | Complete doorsets, windows and similar products | Declared resistance classification |
BS EN 1143-1 | Safes and strongrooms | Certified burglary-resistance classification |
The best standard depends on what you are assessing and what your insurance policy actually requires.
Which Lock Grade Is Best for Your Door?
Choosing the right lock depends on the door construction, existing mechanism and intended security requirements.
Door or situation | Suitable standard or security option to consider |
|---|---|
Timber entrance door with a mortice lock | BS3621-certified lock where appropriate |
Door requiring keyless internal escape | BS8621 arrangement, subject to applicable requirements |
uPVC door with an older Euro cylinder | TS007 three-star anti-snap cylinder |
Composite door with multipoint locking | Correctly sized security cylinder and suitable hardware |
Existing one-star cylinder | Compatible two-star protective hardware or a suitable cylinder upgrade |
Damaged or unreliable locking mechanism | Repair or replacement appropriate to the fault |
Insurance specifies a particular standard | Product matching the exact policy requirement |
A certified lock is only one part of a secure entrance.
The door, frame, hinges, handles and locking mechanism must also be suitable and in good working condition.
Do You Need to Upgrade Your Locks?
Do not replace a working lock simply because it lacks a marketing description such as “high security”.
An upgrade is worth investigating when:
Your insurance policy specifies a standard your existing lock does not meet.
You cannot verify the certification required by your policy.
Your Euro cylinder lacks the level of protection you want against cylinder attacks.
The lock is damaged, corroded or unreliable.
The door or locking mechanism is poorly aligned.
Keys have been lost or cannot be accounted for.
You have recently moved into the property.
There are signs of attempted forced entry.
The condition of the complete door matters.
A certified lock cannot compensate for a badly damaged frame or a multipoint mechanism that no longer engages correctly.
For practical examples of when replacement may be appropriate, see our guide to lock replacement for local homes.
Common Mistakes When Choosing Insurance-Compliant Locks
Understanding a few common misconceptions can help homeowners avoid unnecessary expense.
Assuming every five-lever lock meets BS3621
A five-lever mechanism does not automatically establish compliance with BS3621. The actual certification matters.
Assuming every anti-snap lock is three-star rated
Products marketed as anti-snap locks do not necessarily hold TS007 three-star certification.
Check the product markings and relevant independent approvals.
Believing multipoint locking guarantees cylinder security
A multipoint mechanism and its Euro cylinder perform different functions.
The cylinder may still require an upgrade even when the mechanism operates correctly.
Replacing the entire mechanism unnecessarily
If the multipoint mechanism is working properly, replacing the cylinder alone may provide the required improvement.
Assuming expensive locks automatically satisfy insurance requirements
A more expensive or heavily marketed product is not necessarily the one specified by your insurer.
Always compare the product certification with the policy wording.
Sam’s Expert Advice: Check Your Existing Locks Before Replacing Them
Before paying for a lock upgrade, identify what is already fitted and why a replacement may be necessary.
A timber door may already have a suitable BS3621-certified lock, even if the markings are difficult to see.
Similarly, a uPVC door may have a perfectly functional multipoint mechanism that only needs a correctly specified cylinder upgrade.
Replacing working components without checking their condition or certification can lead to unnecessary expense.
The most practical approach is to inspect the existing hardware, compare it with the insurer’s requirements and choose a replacement only where it addresses a genuine security or compliance issue.
Need Help Identifying or Upgrading Your Door Locks?
If you are unsure whether your locks meet British Standards or your home insurance requirements, AHLP Locksmiths can help identify the hardware fitted to your property.
Sam can assess the existing lock and door, explain the relevant security standards and recommend suitable replacement options where necessary.
Whether you need a BS3621-certified mortice lock, a three-star anti-snap cylinder or assistance with a faulty locking mechanism, the aim is to choose the correct solution rather than replace suitable hardware unnecessarily.
Explore our locksmith services or contact AHLP Locksmiths if you need a lock checked or replaced.
Frequently Asked Questions
What are the main lock grades used in the UK?
The main UK lock security standards include BS3621 for thief-resistant lock assemblies, BS8621 for locks allowing keyless internal escape and TS007 for replacement cylinders and protective hardware. Sold Secure also provides independent security testing across several product categories. These standards assess different products, so the correct one depends on your door and locking system.
What is a British Standard lock?
A British Standard lock is a lock designed and tested against the requirements of a particular British Standard. BS3621 is commonly associated with qualifying locks on timber entrance doors, while other standards apply to different locking arrangements. Check the exact standard number and certification rather than relying only on the words “British Standard”.
What is a BS3621 lock?
BS3621 covers thief-resistant lock assemblies with key operation from both sides. Certified products can include qualifying mortice deadlocks, sashlocks and certain night latches. A BSI-certified product should carry the Kitemark and relevant BS3621 identification.
Does my home insurance require BS3621 locks?
That depends on your individual insurance policy. Some insurers specifically require BS3621-certified locks on relevant external doors, while others accept different locking arrangements. Check your policy schedule and security endorsements before replacing anything. If the requirement is unclear, ask your insurer or broker to confirm it in writing.
Is a five-lever mortice lock automatically insurance approved?
No. Having five levers does not automatically mean a mortice lock complies with BS3621. If your insurance policy specifies BS3621, check the actual certification and product markings rather than relying on the lock’s mechanical design.
What does a three-star lock mean?
A three-star lock usually refers to a cylinder certified to TS007 at the three-star level. A three-star cylinder meets the relevant enhanced security requirements without needing separate two-star protective hardware to achieve that rating. Another recognised arrangement combines a one-star cylinder with two-star security hardware.
Are three-star anti-snap locks required by home insurance?
Not universally. Some insurance policies may specify enhanced cylinder security, but there is no single requirement applying to every UK home. Three-star anti-snap cylinders can provide a worthwhile security improvement even when they are not explicitly required by the insurer.
Is BS3621 better than TS007?
Neither is universally better because they assess different products. BS3621 concerns thief-resistant lock assemblies, commonly encountered on timber doors, while TS007 covers replacement cylinders and protective hardware. The appropriate standard depends on the door type and locking arrangement.
What is the difference between BS3621 and BS8621?
BS3621 covers thief-resistant lock assemblies operated by key from both sides. BS8621 covers thief-resistant lock assemblies that allow keyless escape from inside. The distinction is important where convenient emergency exit is necessary.
How can I tell whether my lock is insurance approved?
Start by checking the exact security requirements in your home insurance policy. If BS3621 is specified, inspect the lock for the BSI Kitemark and standard number. For Euro cylinders, check any TS007 certification and star rating. Compare the product specification with your policy rather than assuming that a lock is acceptable because it is marketed as high security.
Where can I find the BS3621 marking on my door lock?
On many mortice locks, the BS3621 marking appears on the metal forend or faceplate along the edge of the door. Open the door and look for the standard number and BSI Kitemark. If the markings are not visible, identify the manufacturer and model or ask a locksmith to verify the product.
Can I upgrade my uPVC door lock without replacing the entire mechanism?
Often, yes. If the multipoint mechanism is functioning correctly, replacing the Euro cylinder with a suitable enhanced-security cylinder may be sufficient. The replacement must be correctly sized and compatible with the existing door hardware.
Can an insurance company refuse a claim because of the wrong locks?
Failure to comply with an applicable security condition may affect a claim, but the outcome depends on the policy wording, circumstances and relevant insurance law. It is not automatic that every claim involving a non-compliant lock will be refused. Confirm the requirements with your insurer if you are unsure.