Mortice Lock Fitting in West Sussex
Need a mortice lock fitted or replaced? Call Geoff on 07889325487


If you’ve got a wooden front or back door, there’s a good chance it has a mortice lock, the solid lock fitted into the edge of the door itself rather than on the surface. Whether you need a new one fitted, an old one replaced, or you’ve been told by your insurer that you need a British Standard lock, Geoff at GRN Locksmiths can help.
Geoff covers all of West Sussex and into Hampshire, with no call-out fee and a clear price agreed before any work starts.
A mortice lock sits inside a pocket cut into the edge of the door, which is where the name comes from. You’ll find them on wooden doors, and they come in two main types:
A mortice deadlock has a single bolt operated by a key. It’s often fitted alongside a nightlatch for extra security on a front door.
A mortice sashlock combines a deadbolt with a latch, so it can be opened with a handle as well as locked with a key. Common on back doors and side doors.
Mortice locks are also described by the number of levers inside them, usually 3-lever or 5-lever. The lever count matters for security, which is where the British Standard comes in.
This is the part that catches a lot of people out, so it’s worth explaining clearly.
Most home insurers require a mortice deadlock that meets the British Standard BS3621 on wooden front and back doors. To meet that standard, the lock must have at least 5 levers, so a 3-lever lock won’t qualify. A genuine BS3621 lock carries the BSI Kitemark stamped on the faceplate along the edge of the door.
Here’s the thing many people don’t realise: a lock marked simply “5 lever” isn’t automatically British Standard. It needs the actual Kitemark to count. If your policy asks for a British Standard lock and yours doesn’t have it, a claim could be affected.
One more useful point. BS3621 applies to wooden doors only. If your door is uPVC or composite, you can’t fit a mortice lock to it, and your insurer will be looking for full multipoint locking mechanism with a eurocylinder lock.
Most insurers do not specify what type of eurocylinder but we recommend using at least a 1* rated cylinder but preferably a 3* cylinder with a TS007 or Sold Secure diamond rating – there is not a British Standard rating for cylinders as there is for mortice locks, yet. A weak cylinder is what burglars will attack first.
Geoff will always tell you what your specific door actually needs, rather than selling you something that won’t fit.
There are a few common reasons people call Geoff about mortice locks:
Geoff will look at your door and your existing lock first. If you’re replacing a lock, he’ll check whether a like-for-like swap will work or whether the door needs any adjustment to take a new lock. Wooden doors vary, and the pocket for the lock has to be right, so it’s worth having it done properly.
He’ll explain what’s needed, confirm the price, and in most cases carry out the work on the same visit. He carries British Standard mortice locks in common sizes in the van. Before he leaves, he’ll check the lock operates smoothly and that you’re happy with it, and he can provide a receipt confirming the lock meets BS3621 if you need it for your insurer.
As a rough guide, a new mortice lock fitted starts from £100. The final price depends on the type of lock your door needs and whether any adjustment to the door is required. Geoff will always confirm the price with you before starting, and there’s no call-out fee.
GRN Locksmiths covers a wide area across West Sussex and into Hampshire. Geoff is on the road most days and reaches a lot of towns and villages across the region.
In West Sussex this includes Bognor Regis, Chichester, Worthing, West Worthing, Littlehampton, Arundel, Selsey, Pagham, Angmering, Goring-by-Sea, Barnham, Aldwick, West Wittering, Bracklesham, Midhurst, Petworth, Storrington, and Pulborough.
In Hampshire, Geoff covers Emsworth, Havant, and Hayling Island.
Not sure if you’re covered? Call or WhatsApp Geoff on 07889325487 and he will let you know.
Geoff is DBS checked, Checkatrade verified, and has been repairing and replacing locks across West Sussex for years. He’s an independent, family-run business, which means you deal with the person doing the job from start to finish.
Bruce the Golden Retriever occasionally comes along for the ride too, if that helps.
No call-out fee. No VAT on labour. Price agreed before work starts. All work guaranteed.
Open the door and look at the metal faceplate on the edge of the door. A British Standard lock has the BSI Kitemark (a heart-shaped symbol) and “BS3621” stamped into it. If there’s no Kitemark, it probably doesn’t meet the standard. Geoff can check for you.
Yes. Geoff fits BS3621 mortice deadlocks and can provide a receipt confirming the standard for your insurer. If your door is uPVC rather than wood, he’ll explain what you need instead.
A deadlock has just a key-operated bolt. A sashlock has both a bolt and a latch so it works with a handle too. Geoff will advise which suits your door.
Usually, yes, and that’s often the quickest option. If the old lock is a non-standard size, the door may need slight adjustment, which Geoff will explain before starting.
A straightforward replacement on a timber door usually takes under an hour. If the door needs adjustment to take a new lock, it can take a little longer.
Call or WhatsApp Geoff on 07889325487 or use the contact form below.






















Locked out? We will get to you…fast! There’s no call-out fee and no fix no fee.
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