Can I get a replacement window lock key without the original?

Yes. A locksmith can cut a replacement key to the lock by hand using a blank and a file - no original is needed. Alternatively, send a clear photo of your lock or handle to a specialist UK supplier who can identify the model and post a matching key to you within a few days.

How do I identify what type of window lock I have?

Look at the handle fitting. Espagnolette (espag) handles have a square spindle at the base and two fixing screws - common on uPVC windows made from the 1990s onwards. Cockspur handles have a curved spur or tongue and four fixing screws in a square pattern - typical of older uPVC, timber and aluminium windows. Fitch fasteners are pivoting cam-action catches found on traditional timber sash windows. Key-operated locks have a visible keyhole in the handle or frame.

What measurements do I need to order a replacement window lock key?

For espagnolette locks, measure the spindle length (from base to tip) - common sizes are 15 mm to 60 mm - and note the backset. For cockspur handles, measure the backset height (from the base of the handle to the underside of the spur) and confirm whether it is left- or right-handed. Also check for any manufacturer name or logo on the lock body.

How much does window lock key replacement cost in the UK?

Replacement keys bought online typically cost around £4 to £10 each. If the lock needs rekeying by a locksmith, expect to pay from around £55. If the mechanism needs repairing, costs start from around £99. A full lock change starts from £69 labour with City Locksmith London.

What should I do if no replacement key exists for my window lock?

If the lock model has been discontinued or you cannot source a matching key, the safest option is to replace the entire lock unit. A locksmith can advise on a compatible modern equivalent and install it the same day. This is often more cost-effective than extended searching for an obsolete key.

Are window lock keys universal or lock-specific?

Window lock keys are brand- and model-specific, not universal. However, some manufacturers (such as Cotswold) produce keys that fit both their espagnolette and cockspur range. Identifying the handle brand - usually stamped on the back of the handle or the lock body - is the fastest way to find the correct replacement.

Is it worth replacing the whole lock instead of finding a new key?

If the lock is old, corroded or the model is obsolete, replacing the whole unit is often the better option. Modern espag multipoint locks offer significantly better security than older single-point cockspur systems. A locksmith can swap a window lock in under an hour, and a like-for-like lock change starts from £69 labour.

Window Lock Key Replacement UK: Types, Identification & What to Do

If you have lost a window lock key, you need to identify the lock type first - espagnolette, cockspur, fitch or key-operated sash - then either order a brand-matched replacement online or call a locksmith to cut a key to the lock or replace the unit entirely. Replacement keys bought online typically cost £4-£10; locksmith rekeying starts from around £55; a full lock change starts from £69 labour. Acting promptly matters: an unsecured window is one of the most common entry points for burglars in the UK.

Why Window Lock Key Replacement Matters for Home Security

Windows account for a significant proportion of residential break-ins in the UK. A missing or damaged window lock key leaves your property exposed, and the problem is particularly common after moving into a new home where previous occupants have taken or lost the keys.

Knowing which lock type you have - and the fastest route to a replacement key - is an essential part of keeping your home secure. This guide covers every common UK window lock type, how to identify each one, and what to do when a key is lost or a lock fails.

For a broader look at door and window security, see our guide to security door and window lock types in London.

What Are the Main Types of Window Lock in the UK?

UK windows use four principal lock types. Identifying yours correctly is the critical first step before ordering any replacement key.

Lock type	Era / window type	Key feature to spot	Key measurement needed
Espagnolette (espag)	1990s-present, uPVC casement	Square spindle at base; 2 fixing screws	Spindle length (15-60 mm), backset
Cockspur	Pre-late 1990s; uPVC, timber, aluminium	Curved spur/tongue; 4 screws in square pattern	Backset/step height; left or right-handed
Fitch fastener	Traditional timber sash windows	Pivoting cam-action catch at meeting rails	Cam projection; screw centres
Key-operated sash lock	Victorian/Edwardian sash; modern secure models	Visible keyhole in handle or frame	Key profile; lock brand

Espagnolette (Espag) Locks - the Most Common Type

Espagnolette locks are the standard on virtually all uPVC casement windows installed in Britain since the 1990s. The handle turns a square spindle (usually 7 mm) that drives a multipoint locking gearbox running along the edge of the window frame, securing the sash at several points simultaneously.

How to identify an espag lock:

Square spindle protruding from the base of the handle
Two fixing screws aligned vertically with the handle
Handle turns to engage multiple locking points around the frame

What you need to measure for a replacement key or handle:

Spindle length from base of handle to tip (common sizes: 15, 20, 25, 30, 35, 40, 43, 50, 60 mm)
Backset - the distance from the spindle centre to the window edge
Whether the handle is inline (universal) or cranked (left or right-handed)

Espag keys are brand-specific. Check the back of the handle or the gearbox body for a manufacturer name (common UK brands include ERA, Mila, Avocet, Securistyle, Yale).

Cockspur Handles - Older uPVC and Timber Windows

Cockspur handles are found on uPVC windows made before the late 1990s and on many timber and aluminium-framed windows. Instead of a spindle-driven gearbox, the security relies on a curved spur (the “cockspur”) pressing down against a wedge keep on the opposite frame.

How to identify a cockspur handle:

Distinctive curved spur or tongue projecting from the handle body
Four fixing screws arranged in a roughly square pattern (approximately 24 mm x 32 mm centres)
Locking versions have a key button integrated into the handle

What you need for a replacement:

Backset height - from the base of the handle down to the underside of the spur
Handedness - left-handed or right-handed (the spur faces opposite directions)

One important security note: cockspur locks are single-point only. If your property still has original cockspur handles, upgrading to a modern espag multipoint system significantly improves resistance to forced entry. Our residential locksmith service can advise on the best upgrade options.

Fitch Fasteners - Traditional Sash Windows

Fitch fasteners (also called fitch catches) are the traditional lock on timber sliding sash windows, which are common in Victorian and Edwardian properties across London. They work as a pivoting cam that draws the two sashes together at the meeting rail.

How to identify a fitch fastener:

Pivoting oval or teardrop-shaped catch mounted on the inner sash
No spindle - the cam rotates to lock the meeting rails together
Lockable versions have a small keyhole in the cam body

Fitch fasteners are not high-security on their own. For ground-floor or accessible sash windows, a secondary sash stop or key-locking bolt provides a meaningful upgrade.

Key-Operated Window Locks

Separate key-operated locks - bolt-through locks, frame bolts, and handle locks with an integral keyhole - can be fitted to any window type. They are common on PAS 24-rated windows and on ground-floor casements where additional security is specified.

Replacement keys for these locks require either the key code stamped on the lock body or a locksmith to cut a new key to the lock directly.

How to Identify Your Window Lock Without a Key

If you have lost the key and are unsure of the lock type:

Look at the handle base. A square spindle = espag. A curved tongue = cockspur. A visible keyhole = key-operated lock.
Count the fixing screws. Two screws in line = almost certainly espag. Four screws in a square = cockspur.
Check for brand markings. Look on the back of the handle (use a small mirror), on the gearbox body visible at the window edge, or on the keep plate on the frame.
Note the window material and age. uPVC post-1995 = almost always espag. Timber sash = fitch or key-operated. Older uPVC or aluminium = likely cockspur.
Photograph everything. A clear photo of the handle front, the lock body, and any visible text lets a locksmith or online supplier identify the model in minutes.

How to Get a Replacement Window Lock Key

Option 1: Order Online From a Specialist Supplier

Once you have identified the brand and model, replacement window keys are available from UK suppliers for around £4-£10. Some suppliers (such as handlesandhinges.co.uk or lockmaster.co.uk) will identify the correct key from a photo you email to them.

This route works well when:

You can clearly identify the brand and model
At least one window of that type is still accessible and unlocked
The lock itself is in good working order

Option 2: Call a Locksmith to Cut a Key to the Lock

A locksmith can cut a replacement key without the original by picking or manipulating the lock and then impressioning or cutting a new blank to match. This is the best option when no replacement key is available online or the lock model is discontinued.

At City Locksmith London we carry a wide range of window lock key blanks and can cut keys on-site across all London postcodes. Contact us for a free quote.

Option 3: Rekey the Lock

If you want to change which key operates the lock - for example, after moving into a new property - a locksmith can rekey it so that only new keys will work. Window lock rekeying starts from £55 with City Locksmith London.

Option 4: Replace the Entire Lock Unit

If the lock is corroded, seized, discontinued, or simply old and single-point, a full replacement is often the most practical and cost-effective solution. Like-for-like lock change labour starts from £69, and upgrading an older cockspur to a modern multipoint espag system significantly improves your home security.

For a full breakdown of what to expect on cost, see our locksmith price list.

What to Do if the Window Is Locked and You Cannot Open It

If a window is stuck closed because the lock has jammed or the key is lost:

Do not force it. Forcing a jammed espag gearbox can crack the uPVC frame.
Apply lubricant. Silicone-based spray or graphite powder into the keyway can free a stiff mechanism.
Try a flathead screwdriver in the keyway - on simple cam-type locks this sometimes turns the cam, but avoid it on precision espag gearboxes.
Call a locksmith. A professional can open the window without damage in most cases, then replace or rekey the lock on the same visit.

City Locksmith London responds across Greater London within 25 minutes, 24 hours a day, 7 days a week. Request help now.

Common Problems That Cause Window Lock Key Issues

Lost or misplaced keys - particularly common after moving into a new property where previous owners took all window keys
Corrosion and rust - especially on older metal locks or external-facing hardware exposed to moisture
Jammed mechanisms - caused by debris, paint build-up, or worn gearbox components inside espag systems
Broken keys - snapped off in the lock due to wear, forcing or cold weather making metal brittle
Discontinued models - older window lock ranges where replacement keys are no longer manufactured

Enhancing Window Security Beyond the Lock

Replacing or finding a matching key restores baseline security, but consider these additional measures for ground-floor and accessible windows:

Secondary sash stops - limit how far a casement or sash window can be pushed open from outside
Window security film - applied to the glass, it holds shattered panes together and slows entry
Chain locks - allow ventilation while preventing the window opening enough to climb through
Smart window sensors - alert you when a window is opened unexpectedly

For a full overview of window security options, see our guide to security door and window lock types.

When to Call a Professional Locksmith

DIY key replacement works when the lock is accessible, in good condition, and the correct key is available online. Call a professional when:

The window is locked closed and you cannot access it
The lock mechanism is seized, damaged, or corroded
No matching replacement key exists for a discontinued model
You want the security reassurance of a lock change with a new keyed system
You are moving into a property and want all window locks rekeyed to a single new key

City Locksmith London operates 24/7, covers all London postcodes with a 25-minute response time, charges no call-out fee, and uses fully insured, DBS-checked engineers. Our residential locksmith team handles all window lock types - espag, cockspur, fitch, and key-operated - across the full range of uPVC, timber, and aluminium windows.

Get a free quote from City Locksmith London