Keys Explained — Types of Keys, Cutting, and When You Need a Locksmith

Door key types

Mortice keys

Used with mortice locks (the lock that sits inside the door body). Mortice keys have a flat blade with cuts along one or both edges, and a bit or bow that turns in the lock. British Standard mortice locks (BS3621) require a 5-lever mechanism — meaning the key must lift five levers to the right height to throw the bolt. These keys can be cut as spares from a working key, or cut to code if the lock details are known.

Cylinder keys (rim and euro)

The flat, serrated keys used with nightlatches (rim cylinders) and uPVC/composite door cylinders (euro cylinders). These are the most commonly duplicated keys — a hardware shop or key kiosk can cut a spare from a working key in minutes. However, some cylinders use restricted or patented key profiles that can only be cut by an authorised locksmith or supplier, preventing unauthorised copies.

High-security keys

Higher-security locks — particularly those rated TS007 or SS312 — often use restricted key blanks. These can only be cut by authorised dealers with the correct blank. If you’re getting an anti-snap cylinder fitted, ask about key control: it’s part of the security investment.

Car key types

Basic cut keys (older vehicles)

Older cars use a simple cut key with no electronics. These can be cut from a working key or from the vehicle’s key code. A locksmith or key cutter can usually handle these.

Transponder keys

Most cars made after the late 1990s have an immobiliser. The key contains a transponder chip that communicates with the car’s ECU when you start the engine. A correctly cut key that hasn’t been programmed to the car’s immobiliser will turn in the lock but won’t start the engine. Programming requires specialist equipment — a locksmith with automotive programming tools, not a key kiosk.

Remote/key fob keys

Keys with buttons to lock and unlock the car remotely. These contain both a transponder (for the immobiliser) and a remote transmitter (for the central locking). Both elements must be programmed to the vehicle — cutting the blade is just the start.

Smart keys / proximity keys

Newer vehicles use smart keys that communicate with the car passively — you can unlock and start without pressing a button or inserting a key. These are the most complex to replace and typically require a specialist automotive locksmith or the main dealer.

Key cutting vs locksmith: which do I need?

• Spare copy of a standard cylinder key: a key-cutting kiosk or hardware shop can do this from a working key in minutes.
• Spare copy of a mortice key: most hardware shops can cut these from a working key. A locksmith can also cut to code if you don’t have a working key.
• Lost all keys / locked out: you need a locksmith, not a key cutter.
• Car transponder or fob key: you need an automotive locksmith. A standard key cutter cannot program the electronics.
• Restricted or patented key blank: you need an authorised supplier or locksmith.
• New lock with no existing key: a locksmith can key a new lock and cut keys from scratch.

Key FAQs

Can you cut a key without the original?

For door locks, often yes — we can cut to code if the lock details are available, or in some cases pick/decode the lock. For car keys, we need the vehicle registration, V5, and proof of ownership; then we can cut and program a new key.

Why won’t a copy key turn properly?

Usually because the copy was cut from a copy (which accumulates small errors), the original key was worn, or the blank was not the correct profile. We cut from code or a clean original where possible.

How many copies should I have?

For home door keys, we’d suggest one spare minimum per occupant. For car keys, one spare is strongly recommended — an “all keys lost” car job is always more expensive than cutting a spare from a working key.

Can anyone cut a key to my lock?

For standard cylinder keys, yes — any key kiosk can copy them. If key control matters to you (e.g. a rental property), consider a lock with a restricted key profile that can only be cut by an authorised dealer.

Related guides

Lock Types Explained · Lock Security & Insurance · Car Locksmith Finsbury Park

Areas we cover

Holloway · Archway · Highbury · Islington · Stroud Green · Crouch End · Stoke Newington

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