Lock Types Explained (UK Guide)

Most homeowners don't actually know what type of lock they have.

They just know: "It locks."

But different locks serve different purposes — and not all offer the same level of protection.

Here's a simple breakdown of the most common lock types in the UK.

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1) Mortice Lock (Common on Wooden Doors)

A mortice lock is fitted inside the door.

You normally see it on traditional wooden front doors.

There are two main types:

5-Lever Mortice Deadlock (BS 3621)

• Insurance compliant
• Key operated from both sides
• Strong bolt that goes deep into frame
• Very secure when fitted correctly

If your insurer requires BS 3621, this is usually what they mean.

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2) Yale Lock (Nightlatch)

Often called a "Yale lock" (brand name).

You see these on wooden front doors, usually above a mortice lock.

Features:

• Automatically locks when door closes
• Opened from inside with a handle
• Key entry from outside

On its own, it's not enough for insurance in most cases. Best used with a mortice deadlock.

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3) Euro Cylinder Lock (UPVC & Composite Doors)

If you have a UPVC or composite door, you likely have a euro cylinder.

Security level depends entirely on the cylinder quality.

Basic cylinder — no anti-snap protection, easier to attack.

Upgraded cylinder:

• Anti-snap
• Anti-drill
• Anti-pick
• Often TS007 3-star rated

This is one of the most common upgrades we recommend.

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4) Multi-Point Locking System

This is not a cylinder — it's the mechanism inside UPVC/composite doors.

When you lift the handle, hooks, rollers and deadbolts all engage into the frame.

If your handle feels loose or stiff, the mechanism may need adjustment.

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5) Thumbturn Cylinder

Common in flats and apartments. Allows key entry from outside, thumb turn from inside. Often required for fire safety. Make sure it's anti-snap if on a UPVC door.

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Which Lock Is "Best"?

It depends on your door material, property type, insurance requirements, and frame condition.

Quick reference:

• Wooden front door → 5-lever BS 3621 mortice
• UPVC door → Anti-snap TS007 3-star cylinder
• Flat → Thumbturn cylinder + compliant main lock

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The Biggest Security Mistake

People upgrade the lock but ignore door alignment, a weak frame, worn hinges, and a cylinder that sticks out too far. Security is about the whole system.

Not sure what you have? Call: 020 3051 8388