Most people can't name the type of lock on their front door — and why would they? It works, you use it, you don't think about it. But when something goes wrong, when you're trying to buy a replacement, or when your insurer asks whether you have a five-lever mortice lock, knowing the difference matters. This guide covers the most common lock types found on UK homes, how to identify them, and what each one means for your security.
Euro Cylinder
Found on: uPVC doors, composite doors, aluminium doors, and some timber doors with multi-point locking.
The euro cylinder is the most common lock type in modern UK homes. It's the oval-shaped barrel your key goes into, typically located in the centre of the door handle on uPVC and composite doors. You'll recognise it by its distinctive oval shape and the fact that it sits within a handle plate rather than being mounted independently on the door.
Euro cylinders are measured in millimetres — the total length, and the measurement from each end to the fixing screw hole in the centre. A typical front door cylinder might be 35/35mm (35mm on each side, totalling 70mm) or 40/40mm. Getting the right size matters when replacing one — too short and it won't reach the handle mechanism, too long and it protrudes and becomes vulnerable to snapping.
Security consideration: Standard euro cylinders are vulnerable to lock snapping — a technique where lateral force is applied to the protruding part of the cylinder to break it at its weak midpoint. Anti-snap cylinders (rated TS007 one star or above) are specifically engineered against this. If your cylinder doesn't have visible star rating markings, assume it's a basic model.
Mortice Lock
Found on: Timber doors — particularly front doors on older properties, Victorian and Edwardian terraces, and many semi-detached homes built before the 1990s.
A mortice lock is set into a pocket (the "mortice") cut into the body of the door. You won't see much of it — typically just a keyhole on the face of the door, and a faceplate on the door edge. The key goes directly into the face of the door, usually in a separate keyhole below (or sometimes above) the door handle.
Mortice locks come in different lever configurations — typically two, three, or five levers. More levers means greater complexity and better security. The relevant British Standard for external mortice locks is BS3621, which requires a minimum of five levers and various anti-tamper features. Many home insurers specify BS3621 compliant locks as a condition of cover on properties with timber doors.
How to check yours: Open the door and look at the faceplate on the door edge. A quality five-lever mortice lock will typically have "BS3621" or a BSI Kitemark stamped on the faceplate or visible when the bolt is extended.
Nightlatch (Yale-type Lock)
Found on: Timber front doors, particularly on older and period properties. Very common across older housing stock in Stourbridge, Halesowen, and the surrounding area.
A nightlatch is the spring-loaded latch with a large, flat cylinder on the outside of the door — what most people call a "Yale lock" (Yale being the most well-known manufacturer, though many brands make them). The key goes into the round cylinder on the outside of the door, and there's typically a small lever or knob on the inside to operate it.
A basic nightlatch provides only a single locking point and can sometimes be slipped open with a credit card if the door frame doesn't fit tightly. British Standard nightlatches (BS3621 compliant) include additional security features including a deadlocking function and anti-shimming protection.
Security consideration: A nightlatch on its own is not adequate security for an external door. Paired with a five-lever mortice deadlock below it — which is what you'll often see on a properly secured timber front door — the combination provides much better protection. If your front door has only a nightlatch and no mortice lock, it's worth addressing.
Rim Lock
Found on: Older timber doors, sometimes rear or side doors on period properties.
A rim lock is surface-mounted on the inside face of the door rather than set into the door body. It's a visible box on the inside, with a corresponding box (the striking plate or rim cylinder) on the frame. Rim locks are less common on modern properties but still found on older housing stock and some outbuildings.
Standard rim locks vary considerably in quality. British Standard rim locks meeting BS3621 exist and provide good security, but many older rim locks are basic and offer minimal resistance to forced entry.
Multi-Point Locking System
Found on: All modern uPVC and composite doors (in combination with a euro cylinder), and some modern timber doors.
Strictly speaking this isn't a lock type in isolation — it's a system. The multi-point mechanism is the strip of hardware that runs the height of the door edge, with the euro cylinder providing the deadlocking function and the gearbox behind the handle driving the locking points (hooks, rollers, and bolts) when you lift the handle.
Multi-point systems provide significantly better security than a single-point lock because they engage the door frame at multiple points along its length, making forced entry much harder. The weakness, as noted, tends to be the euro cylinder itself — which is why upgrading to an anti-snap cylinder matters.
Padlocks
Found on: Gates, garages, outbuildings, sheds.
For security purposes, the key things to look for in a padlock are: a closed shackle design (where the metal loop is recessed into the padlock body, making it resistant to bolt cutters), a quality cylinder mechanism, and a body that resists attack. Padlocks sold in budget ranges from DIY stores are frequently of poor quality — the money spent on a good closed-shackle padlock on a gate or outbuilding is worth it.
Not Sure What You Have?
If you're trying to identify your lock type, the quickest approach is to WhatsApp a photo to us on 07961 169 681. A photo of the lock from outside and the door edge (when the door is open) will usually be enough to identify it, confirm its security level, and advise on whether it meets your insurer's requirements. No obligation — happy to advise.