What Is Lock Bumping and Why Should You Care?
The attack that opens over 90% of UK front door locks in under 30 seconds -- without leaving a mark.
Lock bumping works like this. A specially cut key -- called a bump key or 999 key -- is inserted into a standard pin tumbler cylinder. The key is pulled back one click, then struck sharply with a screwdriver handle or small mallet while the attacker applies gentle turning pressure. The impact sends the driver pins jumping above the shear line for a fraction of a second, and in that moment the cylinder turns. The door opens. No scratches. No forced entry marks. No sign anything happened at all.
This is not theoretical. Bump keys for common euro cylinders are sold openly online for a few pounds. The technique takes about ten minutes to learn. A standard euro cylinder lock -- the type fitted in the vast majority of uPVC and composite doors across South London -- uses basic pin tumblers with smooth driver pins that respond predictably to the bump impact. That predictability is the vulnerability.
The insurance problem is real. If your home is broken into via bumping, there will be no evidence of forced entry. Some insurers have rejected claims on this basis, arguing that the door was left unlocked. A lock rated to TS007 3-star or SS312 Diamond with certified anti-bump protection removes this risk entirely. It also demonstrates you took reasonable steps to secure your property -- which is what your policy expects.
An anti-bump cylinder lock defeats this attack at the mechanical level. Instead of standard smooth driver pins, these cylinders use spool pins (also called mushroom pins) -- driver pins with a narrowed waist that catch at the shear line instead of bouncing past it. When a bump key strikes a spool pin, it creates a false set: the pin appears to clear the shear line but the waist catches on the cylinder wall, preventing rotation. Higher-end locks like the Brisant Ultion use a combination of spool pins, serrated pins, and a secondary locking mechanism that activates if manipulation is detected.
We supply and fit anti-bump cylinder locks across South London -- from Croydon and Wallington to Purley and Kenley. Every cylinder we fit includes anti-bump, anti-snap, anti-drill and anti-pick protection as standard. Read more on our about us page, or check our locksmith advice blog for more on home security.
Anti-Bump Cylinder Lock Key Features
What makes a bump-resistant cylinder different from the standard euro cylinder on your door right now.
Security Rating
TS007 3-Star or SS312 Diamond. Tested against bumping, snapping, picking, and drilling. BSI Kitemark certified.
Pin Technology
Spool pins, serrated pins, or magnetic pin systems. These catch at the shear line during bump attacks instead of bouncing past it.
Best Used For
uPVC doors, composite doors, and any door with a euro profile cylinder. Front doors, back doors, patio doors.
Price Range
From £200 supplied and fitted. Includes certified anti-bump cylinder, professional installation, and all keys.
Anti-Bump vs Anti-Snap: Do You Need Both?
They protect against different attacks. Here is what each one stops, why you need both, and which doors are most at risk.
Two Different Attacks, One Cylinder
Bump Attack
Manipulation -- no visible damage
A bump key is struck while turning pressure is applied. The driver pins jump above the shear line, allowing the cylinder to rotate. No scratches, no marks -- insurers may argue the door was left unlocked.
Stopped by: spool pins and anti-manipulation features
Snap Attack
Brute force -- visible damage
The exposed cylinder is gripped with pliers and snapped in half. The broken section is removed and the mechanism turned with a screwdriver. Fast, loud, and leaves clear evidence of forced entry.
Stopped by: sacrificial snap line and reinforced inner core
The bottom line: a lock that resists bumping but can be snapped is only half-protected. Certified cylinders rated to TS007 3-star defend against all four attack methods -- bumping, snapping, picking, and drilling. That is why we only fit cylinders with full multi-attack protection. Our anti-snap cylinder lock page covers the snap side in detail.
Is Your Current Lock Vulnerable?
Three signs your euro cylinder can be bumped open.
Flat-profile zigzag key
If your key has a standard zigzag cut edge (not dimple indentations), your cylinder almost certainly uses smooth driver pins that respond to bumping.
No TS007 or Kitemark stamp
Check the face of the cylinder for a BSI Kitemark or TS007 rating. No stamp means no tested anti-bump protection.
Original builder-supplied lock
If the lock has not been changed since the door was installed, it is almost always a basic cylinder. Door manufacturers fit the cheapest locks they can.
Door Types Most at Risk
Any door with a euro profile cylinder slot is a potential target for bump attacks.
uPVC Doors
Highest Risk
Almost always fitted with a basic euro cylinder from the factory. Standard smooth driver pins with zero bump resistance. The most common target in South London.
Composite Doors
High Risk
Stronger door panel, but uses the same euro cylinder slot. If the builder fitted a basic cylinder, it is bumpable regardless of how solid the door itself is.
Timber + Euro Cylinder
Moderate Risk
Some wooden doors use multipoint locks with euro cylinders. If yours does, the same vulnerability applies. Traditional mortice locks are not bumpable.
Insurance and the "No Forced Entry" Problem
Bump attacks leave no trace of forced entry. Some insurers have used this to reject claims, arguing the door was left unlocked.
Fitting an anti-bump cylinder rated to TS007 3-star or SS312 Diamond closes this gap. We provide a receipt and product certificate showing the security rating for your insurer. If you have been burgled recently, upgrading is the first step to preventing it happening again.
Brands We Fit
Brisant Ultion
SS312 Diamond. Spool + serrated pins + lock-down mode. £2,000 break-in guarantee.
Avocet ABS MK3
SS312 Diamond + TS007 3-star. Patented magnetic pin anti-bump system.
Yale Platinum 3-Star
TS007 3-star. Anti-bump, anti-snap, anti-drill, anti-pick. Accepted by all insurers.
Our Anti-Bump Lock Services in South London
We carry Ultion, Avocet, and Yale anti-bump cylinders on the van. Same-day fitting across all South London postcodes.
Supply and Fit
New anti-bump cylinder supplied, measured, fitted and tested. Includes all keys and multipoint lock adjustment.
from £200Repair
Stiff key or jammed cylinder? We diagnose on-site. Often a realignment or lubrication resolves it without full replacement.
from £120Replacement / Upgrade
Replacing a basic euro cylinder with a certified anti-bump unit. We remove the old lock, fit the upgrade, and test everything.
from £200Emergency Call-Out
Bumped lock or break-in attempt? We respond within 30 minutes, secure the door, and fit an anti-bump cylinder on the spot.
from £120How It Works
Three steps from first call to a fitted, tested anti-bump cylinder on your door.
Call or WhatsApp
Tell us about your door and current lock. We give you a fixed price over the phone. Send photos on WhatsApp if you want us to identify your lock type first.
We Arrive in 30 Minutes
DBS checked locksmith arrives with anti-bump cylinders on the van. We measure your door, confirm the cylinder length, and show you the options before starting.
Lock Fitted, Keys Handed Over
New anti-bump cylinder installed and tested. We check the multipoint locking engages smoothly, hand over all keys, and give you a receipt for your insurer.
Why Choose Locksmith South London?
We are not a call centre. We are a local locksmith who fits anti-bump locks on doors across South London every week.
DBS Checked Locksmith
Criminal record checked, ID carried on every job.
No Call-Out Fee
You only pay for the work. No fee for turning up.
30-Minute Response
Local to South London. We arrive fast.
5.0 Google Rating
Verified reviews from real South London customers.
Fully Insured
Public liability insurance on every job.
Fixed Prices -- No VAT
The price we quote is the price you pay.
TS007 and SS312 Certified Stock
We only fit tested, certified anti-bump cylinders.
Free Security Audit
We check all external doors and advise on weak points.
Workmanship Guarantee
All fitting work guaranteed. Problem? We come back.
One Locksmith, Start to Finish
The person you speak to is the person who fits your lock.
Anti-Bump Cylinder Lock Fitting Costs South London
Fixed prices. No VAT. No call-out fee. The price we quote on the phone is the price you pay when we finish.
Emergency Lockout
Locked out? We open the door and can fit an anti-bump cylinder at the same time.
from £120
Lockout only. Lock upgrade extra.
Euro Cylinder Change
Standard euro cylinder replacement without the anti-bump upgrade.
from £135
Supplied and fitted.
Anti-Bump Upgrade
TS007 3-star or SS312 Diamond cylinder with full anti-bump protection, supplied and fitted.
from £200
Includes all keys and testing.
BS3621 Mortice Lock
For timber doors. 5-lever mortice deadlock to BS3621 insurance standard.
from £180
Supplied and fitted.
All prices are fixed and include labour. No VAT. Card or cash accepted. Contact us for a free quote.
What Our Customers Say
Recent reviews from customers who had anti-bump cylinder locks fitted in South London.
"I read about bump key attacks online and got worried -- our front door had the original euro cylinder from when the house was built. Called Locksmith South London and they fitted an Ultion anti-bump lock the same afternoon. The locksmith showed me how easy the old lock was to compromise. Really glad I made the call."
Tom H.
Wallington, SM6
"My insurer told me I needed a TS007 3-star cylinder to keep my policy valid. Locksmith South London came out the same day and fitted an Avocet ABS anti-bump lock. They gave me a certificate confirming the lock specification which I sent straight to the insurance company. Sorted in one visit."
Priya S.
Coulsdon, CR5
"I manage four flats in South Croydon and needed all the front door cylinders upgraded. The locksmith replaced the old euro cylinders with Yale 3-star anti-bump versions across all four doors in one visit. Good price for the bulk job and the tenants all got their own keyed sets."
Chris L.
South Croydon, CR2
Frequently Asked Questions
Common questions about anti-bump cylinder locks answered by our locksmiths.
What is lock bumping and why is it a risk?
Lock bumping uses a specially cut bump key inserted into a standard pin tumbler cylinder. The attacker strikes the key with a blunt object while applying light turning pressure. The impact forces the driver pins above the shear line for a split second, allowing the cylinder to turn. A standard euro cylinder with no anti-bump protection can be opened this way in under 30 seconds without visible damage to the lock.
How does an anti-bump cylinder lock prevent bumping?
Anti-bump cylinders use modified pin configurations that defeat the bump technique. The most common approach is spool pins (also called mushroom pins) -- driver pins with a narrowed waist that catch at the shear line instead of bouncing cleanly past it. Higher-end cylinders like Ultion use a combination of spool pins, serrated pins, and a secondary locking mechanism that activates if manipulation is detected.
What is the difference between anti-bump and anti-snap protection?
Anti-bump protection stops manipulation attacks through the keyway using bump keys or pick tools. Anti-snap protection stops physical force attacks where the cylinder is snapped with pliers. They defend against different threats. A quality cylinder rated to TS007 3-star or SS312 Diamond includes both anti-bump and anti-snap protection in one unit, along with anti-drill and anti-pick resistance.
How much does it cost to fit an anti-bump cylinder lock in South London?
We charge from £200 for an anti-bump cylinder upgrade, supplied and fitted. This includes a TS007 3-star rated cylinder with anti-bump, anti-snap, anti-drill and anti-pick protection. There is no call-out fee and no VAT. A standard euro cylinder change without the security upgrade starts from £135.
Which anti-bump lock brands do you recommend?
We fit Brisant Ultion (SS312 Diamond rated, molybdenum construction with lock-down mode), Avocet ABS MK3 (dual SS312 Diamond and TS007 3-star rated, uses patented anti-bump pin system), and Yale Platinum 3-Star (TS007 3-star, widely accepted by insurers). All three include full anti-bump protection alongside anti-snap, anti-drill and anti-pick resistance. We carry all brands on the van.
Can I tell if my current lock is vulnerable to bumping?
If your euro cylinder has a standard pin tumbler mechanism with a flat-profile key (the classic zigzag-cut key), it is almost certainly bumpable. Look for a TS007 rating or BSI Kitemark stamped on the cylinder face. If there is no marking, or the lock was fitted before 2010, it very likely uses standard driver pins with no anti-bump protection. Dimple-key cylinders and cylinders with security-profile keys offer better resistance.
Do I need both anti-bump and anti-snap protection?
Yes. Bump attacks and snap attacks target different weaknesses in euro cylinders. A lock that resists bumping but can be snapped still leaves your door vulnerable. Modern certified cylinders rated to TS007 3-star include protection against all four attack methods: bumping, snapping, drilling and picking. Fitting a cylinder with only one type of protection is a false economy.
Related Lock Types
Explore other security locks we supply and fit across South London.
Areas We Cover in South London
Anti-bump cylinder lock fitting across every South London postcode.
Explore the Site
Related Locks & Problems
Locations
Serving postcodes: CR0, CR2, CR3, CR5, CR7, CR8, SM1, SM2, SM3, SM5, SM6, SW16, SW17, SW19, SE25
Need an Anti-Bump Cylinder Lock Fitted in South London?
Call now for a fixed price over the phone. No call-out fee, no VAT. We carry Ultion, Avocet, and Yale anti-bump cylinders on the van and can fit same day.
Card or cash accepted. Available 24/7.
24/7 emergency locksmith serving South London since 2015 — trusted by homeowners, landlords and businesses across Sutton, Mitcham, Wallington, Cheam, Purley and surrounding areas.