Posted on January 18, 2021 14:05 by matan

British Standard Locks

A standard is something that everyone agrees on as an acceptable level of performance. It provides an expectation that a product or service will reach a recognised degree of competence. Thus a standard can be considered trustworthy as it has undergone tests by experts against known needs. 

For locks, the British Standards Institute (BSI) is the national organisation that oversees UK standards. British Standard locks are laboratory-tested against set criteria so that when you use one, you know that it is a quality product that will perform reliably. 

Every British Standard lock has a Kitemark symbol with a number on the faceplate. The number refers to the standard it has met, and there is often a date stamp which indicates the year of the standard.

Standard lock test numbers

There are different standards for different kinds of doors:


British standard (BS)3621 is the most common standard lock you will encounter. This standard first came into use in 1963. You often find this type of lock fitted to the front and back doors and usually on wooden doors. The BS3621 needs a key to open it both inside and outside.

This standard indicates that the lock resists burglary attempts such as breaking the lock’s cylinder, picking, and drilling the lock. There should also be at least 20mm of bolt projecting into the keep on the door frame to resist impact. Also, there must be at least 1,000 different shaped keys, so that the likelihood of someone having a key to fit the lock is remote.

The types of locks which are most likely to have BS3621 standard are sash locks and deadlocks. These might be mortice sash locks and deadlocks or Euro cylinder sash locks and deadlocks. You will also find the BS3621 standard on rim cylinder night latches and rim locks. For a mortice lock to have a BS3621 standard, it must have five levers.


You may find references to BS3621 locks being “Insurance Approved”. This type of comment is incorrect because no lock is universally “Insurance Approved”. You have to look at your specific insurance schedule to determine the requirements for your insurance cover. However, insurers often consider a BS3621 lock as a standard requirement.


You should note that the BS3621 does not apply to multipoint locks. For multipoint locks, the equivalent standard is the Publicly Available Standard (PAS)3621. Multipoint locks are the locks seen as a long metal strip running down your PUCv or composite door with multiple hook bolts, cams or pins as the locking points. They have the same burglar-resistant standard as the BS3621 lock.


You won’t find the BS8621 fitted to houses very often; it is more likely to be used in flats and apartment blocks. BS8621 is a newer standard than BS3621; it came into use in 2004. This lock needs a key to open it from the outside, but has a thumb turn on the inside which overrides the lock. The BS8621 standard lock allows for a rapid exit without the need for a key, which is why it is a popular choice for flats and apartments where emergency exits via fire escapes may be necessary. You should be careful when installing this lock so that there is no adjacent letterbox or window which may give burglars access to the thumb turn.

You will find BS8621 locks on mortice sash locks and deadlocks, Euro cylinder sash locks and deadlocks and rim cylinder locks.


The PAS8621 has the same functions and standards as BS8621, but, like the PAS3621, it is the version used for multipoint locks found on PVCu and composite doors.


The BS10621 is less common, but you might find it in commercial properties and situations where the last person out locks the door. This standard came into use in 2007 and incorporates elements of both the above locks. You can open it with a key from the outside and only lock it from the outside. This function means that burglars, having gained entrance via a window, cannot let themselves out through the door. The danger of this function is that you could find yourself locked in. 

The BS10621 is tested using the same criteria as BS3621 and BS8621. Like the other locks you can find it on mortice sash locks and deadlocks, Euro cylinder sash locks and deadlocks and rim cylinder locks.


This lock has the same uses and standards as BS10621 but is used for the multipoint locks of PVCu and composite doors.

TS007 and SS312 Diamond Approved cylinders

One of the methods used by burglars to gain entry is by snapping your door lock. Snapping the lock means breaking the lock’s cylinder because once that has been broken the rest of the lock is rendered useless.

There are two nationally recognised standards for anti-snap cylinders. The TS007 and SS312 Diamond Approved cylinders were developed and tested precisely to combat his forced entry method. Since the introduction of the SS312 Diamond Approved cylinder (developed in 2010) and the TS007 (in 2011), lock snapping has declined.

You can fit anti-snap locks on any type of external door, front door, back door or patio door and any kind of material, although they are most often found on PVCu doors.


You should note that there are three specifications of the TS007. For a lock which is proof against snapping you need the TS007 3-star Euro lock rating. The TS007 3-star cylinder achieves this standard all in one go. The alternative is to install a TS007 1-star cylinder and TS007 2-star door furniture which combine to complete the 3-star rating.


The TS007 1-star is a basic cylinder that meets specific minimum requirements such as resistance to lock bumping. It doesn’t meet the full TS007 needs unless paired with TS007 2-star door furniture including handle and escutcheons.

Sold Secure Diamond Approved 

This type of cylinder is called a Sold Secure (SS)312 Diamond Approved Standard cylinder. Locksmiths recognise this approval standard as one of the best cylinders you can get for proof against lock snapping. You can find SS312 Diamond Approval cylinders on a wide range of locks made by different manufacturers.

If you need to upgrade your locks to meet British Standard requirements, change your locks to an anti-snap cylinder, or would like advice on any aspect of your home or business security don’t hesitate to contact Keys4u locksmith on:

Tel 033 330 52993

Email[email protected]

Related services

Door Lock Installation 

Door Lock Upgrade 

Smart Locks 

Digital Door Viewers 

Security Upgrades 

Window Lock Replacement And Repairs

Door Lock Replacement 

Is it worth upgrading my lock to the latest version?

Having the latest version of a lock is not the most important thing. However, your locks must be BS or PAS standard if you want the best security. It is also essential that the lock Euro cylinder meets the TS007 3-star or SS312 Diamond Approved Standard to have the latest security features. So if you have not changed your locks for more than ten years, it is worth examining them or ask your local Keys4u locksmith to look at them to make sure they are still as effective as possible.

Which is the best cylinder, a TS007 3-star or a SS312 Diamond Approved Standard?

They are both excellent cylinders. The difference between the standards is how they are tested. Both types of cylinders are tested using tools for a set amount of time to try to overcome the cylinder. The TS007 3-star is tested over a more extended period than the SS312 Diamond, but a heavier toolset is used when testing to try to breach the SS312 Diamond. Most locksmiths agree that the SS312 Diamond Approved Standard is the more challenging test standard.

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