Mortice Locks & Yale Nightlatches

A Yale-type nightlatch — the kind with a latch bolt that springs back when you close the door — is convenient for day-to-day use, but on its own it offers only limited security. A deadlock provides a second, independent bolt that cannot be pushed or sprung open: the door stays shut until someone physically turns a key from either side. Together, the nightlatch handles the everyday in-and-out while the mortice deadlock adds the reinforcement that most home-insurance policies specifically require. Many insurers in the UK ask for a BS3621 kitemarked deadlock, which meets a tested standard for anti-pick, anti-drill, and bolt strength — if your existing mortice lock pre-dates that standard or was never marked to it, you may find a claim disputed after a break-in.

On period terraces near Streatham Common station, timber doors are typically thick enough to house a full-size 3-inch or 2.5-inch mortice case. On slimmer internal flat doors or on doors that have been replaced over the decades, the timber rebate may be shallower, and a different case depth is needed. Our technicians measure the stile width before recommending a lock, so you never end up with a case that weakens the door by sitting too close to the edge. Where a door shows signs of historic damage or previous forced entry — something we see fairly often on older rental properties along Leigham Court Road — we will also point out any timber repairs that should accompany the new lock fitting to restore the full integrity of the door.

Replacing a mortice deadlock begins with removing the existing lock case from the mortice pocket cut into the door edge, along with its keep (the striking plate in the frame). The new BS3621 case is fitted into the same pocket where dimensions allow — on many Streatham Victorian doors this is straightforward — or the pocket is carefully extended if the new case is deeper. The escutcheons (the keyhole cover plates) are aligned, and the keep is recessed into the frame so the bolt engages cleanly without rattling. A deadlock that is not aligned precisely will either feel stiff from the first week or begin to wear badly within months, so this stage is not rushed. The whole job, including testing from both sides of the door, typically takes under an hour on a standard timber door.

Fitting or replacing a Yale-type nightlatch follows a similar process. The existing rim lock body is unbolted from the door face, the cylinder (the barrel that accepts the key) is removed from the outside, and the keep on the frame is unscrewed. A new nightlatch is fitted using the original fixing holes where possible, keeping the door face clean. If the old latch has left a legacy of oversize holes or the door has been repainted around it, our technicians carry the materials on the van to make good the surface before fixing the new lock. We carry a range of cylinder sizes to suit varying door thicknesses, and we always test the snib (the small lever that holds the latch open) and the deadlocking feature before considering the job done. If you need the work done urgently — a lock that has failed on a weekday evening or over a bank holiday — call 020 4530 9860 and we will send someone straight away.

There is a meaningful difference between a lock that is broken and one that is simply no longer adequate. A mortice deadlock manufactured before the BS3621 standard was widely adopted, or one that shows signs of wear on the levers, is technically functional but may not satisfy your insurer or offer the resistance a modern lock provides. The same applies to a Yale nightlatch: an older rim lock with a standard cylinder can be vulnerable to methods that a higher-security anti-snap or anti-pick cylinder resists. When we attend a property in Streatham for what starts as a repair call, we always advise honestly — if the existing lock can be serviced and will perform reliably, we say so. If an upgrade is the more sensible option, we explain why without pressuring you.

A lock change is also the right course after a tenancy ends, following a burglary or attempted break-in, or when keys have been lost and you are uncertain how many copies are out there. Landlords and letting agents managing properties around Streatham High Road frequently call us between tenancies precisely for this reason. Changing the lock (rather than just the cylinder, which is an option on rim locks) gives complete confidence that the new keys are the only ones in circulation. We can discuss which approach suits your door and your situation on the phone before anyone travels out, so you have a clear picture of what the work involves before we arrive.

We do not publish set figures for lock replacement, because the final quote depends on several honest variables: the type of lock and specification needed (a standard BS3621 case costs differently from a high-security variant with additional anti-pick levers), the time of day or night you call (evening, weekend, and bank-holiday rates differ from standard daytime rates), travel to your specific postcode within the Streatham area, and whether any additional parts or minor timber repairs are needed on the day. What we commit to absolutely is confirming the exact price with you on the phone before our technician travels out — there are no surprises on the invoice.

On arrival, our technician will inspect the door and confirm the agreed scope of work before starting. If anything unexpected comes to light — for instance, an unusually shallow stile on an older Streatham conversion that affects the choice of lock case — we will explain the options and agree any adjustment before proceeding. We carry a broad stock of lock cases, rim locks, cylinders, keeps, and fixings on the van, so the majority of jobs are completed in a single visit. For anything that cannot wait, we are usually with you in about 30 minutes of your call — we send a locksmith straight away and do not leave you waiting for a callback before dispatching. To get a clear, up-front quote and arrange attendance, call 020 4530 9860 any time — we answer 24/7.

Our team operates across Streatham, Streatham Common, Streatham Hill, Streatham Vale, and neighbouring areas in SW16 and beyond. We know the housing stock here: the deep-stiled front doors on the Edwardian semis near Streatham Common park, the slim-framed communal entrance doors on purpose-built blocks, and the mix of original timber and replacement uPVC doors on the streets running off Streatham High Road. That local familiarity matters when a technician arrives and needs to make a quick, accurate judgement about which lock case will fit and perform best without unnecessary modification to the door. We work for private homeowners, tenants (with appropriate verification of their right to access the property), landlords, and managing agents — and we are fully insured for all residential lock work.