Five Reasons You Should Change Your Locks Right Now

There are moments when changing your locks is not just a sensible precaution — it is a necessary response to a specific situation. This guide covers five urgent scenarios that homeowners and tenants across South London encounter, each with the associated risk level, the correct response, an estimated cost and an honest urgency rating. If your situation appears below, act on it — the cost of a cylinder change is consistently less than the cost of what can follow if you do not.

Reason 1: You Have Just Moved Into a New Property

Risk level: High. The key history of any property you have moved into is effectively unknown. Previous occupants may have given copies to neighbours, friends, cleaners, tradespeople or anyone who needed access over the course of their tenancy or ownership. Estate agents, viewing agents and maintenance contractors also frequently hold keys during the sales or rental process.

The fix: Change all external door cylinders on the day you collect the keys or before you move your belongings in. For a standard three-bedroom property with a front and back door, budget £100 to £160 for cylinder replacements including parts and labour. Specify anti-snap euro cylinders rather than standard alternatives — the cost difference is around £15 to £20 per lock and the security benefit is substantial.

Urgency: Change before you sleep there.

Reason 2: Your Keys Were Lost in a Public Place or Stolen

Risk level: High to critical, depending on whether the keys carry any identifying information. A set of house keys found in the street with a name, address or loyalty card is a direct invitation to a burglar who can now identify the property and observe when it is unoccupied. Even without identification, keys lost near your home present an elevated risk.

The fix: If there is any possibility the keys are in the hands of a stranger, change the locks the same day. Do not wait to see whether they turn up. A cylinder replacement on a standard front door costs between £60 and £100 including fitting and typically takes under 30 minutes. Our emergency locksmith service covers Sutton and South London for same-day cylinder changes.

Urgency: Same day without exception if the keys are lost outside your home or were stolen.

Reason 3: After a Break-In or Attempted Break-In

Risk level: Very high. A property that has been burgled is at elevated risk of a repeat visit. Burglars sometimes return because they know the layout of the property, have information about what else is inside, or know the original entry point has not been properly secured. An attempted break-in that did not succeed is also significant — it often means the intruder assessed the property as a viable target and may return with better preparation or tools.

The fix: Replace any lock that was damaged, bypassed or attacked during the incident. Do not simply re-fit an existing cylinder that has been forced, drilled or subjected to snapping. If the entry was made by kicking the door rather than attacking the lock, also check the strike plate, frame and hinges — these are often damaged even when the lock was not the primary point of failure. Budget £80 to £200 depending on the number of locks affected and whether frame repairs are also needed.

Urgency: Same day — before leaving the property unsecured overnight.

Reason 4: Your Locks Are Visibly Worn or More Than Ten Years Old

Risk level: Moderate to high. Lock cylinders wear with every use. The springs and pins that operate the mechanism lose precision over time, making the lock progressively easier to pick and more vulnerable to other attack methods. A cylinder that is visibly discoloured, stiff to operate, or allows the key to jiggle excessively when fully inserted is giving you clear warning signals. Builder-grade cylinders fitted to many properties during construction were never adequate by current standards and should be considered due for replacement after ten years regardless of visible condition.

The fix: Replace the cylinder with a current anti-snap, anti-pick alternative rated to TS007 3-star. Confirm whether the lock body (for mortice locks) meets BS3621 — if it does not, replace the full lock assembly rather than just the cylinder. Budget £60 to £120 per lock for a quality cylinder replacement including fitting.

Urgency: Within the next four weeks.

Reason 5: Your Home Insurance Requires an Upgrade

Risk level: Financial and legal. Many UK home insurance policies specify that external doors must be fitted with BS3621-certified locks as a condition of cover. If your current locks do not meet this standard and you make a claim following a break-in, your insurer may reduce or refuse the payout on the grounds that the specified security measures were not in place. This is not a theoretical risk — insurers do contest claims on this basis, and the standard terms of most comprehensive policies include lock-quality clauses.

The Secured by Design scheme tests and certifies products that meet or exceed BS3621 performance requirements. Specifying an SBD-approved lock when upgrading provides the strongest available evidence of compliance if a claim is ever made.

The fix: Have your current locks checked against your policy wording. If they do not comply, upgrade before your next renewal. A BS3621-rated five-lever mortice deadlock for a timber door typically costs £80 to £150 including fitting. A TS007 3-star euro cylinder assembly for a uPVC door costs £60 to £120 including fitting.

Urgency: Before your next insurance renewal date.

Frequently Asked Questions

Can I change my own locks, or do I need a locksmith?

A straightforward cylinder replacement on a uPVC door is within the capability of a confident DIYer with basic tools, provided you measure the existing cylinder correctly and purchase the correct size. More complex work — mortice lock replacement, frame repair, alignment adjustment — requires a trained locksmith to avoid creating new vulnerabilities in the process.

Will changing my locks void my insurance?

No — but changing to a lower-quality lock than your policy specifies might affect your cover. Upgrading to a BS3621 or TS007 3-star product is always safe from an insurance perspective and may reduce your premium. Notify your insurer after any significant upgrade.

How long does a lock change take?

A euro cylinder replacement on a standard uPVC front door takes 15 to 30 minutes. A full mortice lock replacement on a timber door takes 30 to 60 minutes. If frame repairs are also needed following a break-in, allow an additional 30 to 60 minutes depending on the extent of the damage.

How many keys do I get with a new lock?

Most professional locksmith cylinder replacements include three keys as standard. Additional keys can be cut at the time of replacement or later; some high-security cylinders have patent-protected profiles that restrict where copies can be made, which adds a layer of security against unauthorised duplication.