A Chubb key is the key to a lever lock, and in Britain the name has stretched to cover almost any mortice deadlock key, whoever made the lock. It all began with Jeremiah Chubb’s detector lock of 1818. Here’s what the term means, how to read and date an old Chubb key, and how to get a new one.
Key takeaways
- A Chubb key has a round shank and a flag-shaped bit cut in steps, one step for each lever in the lock.
- In everyday British speech a “Chubb” is any lever mortice deadlock, whoever made it, much as a vacuum cleaner is a “Hoover”.
- Insurers usually ask for a lock made to BS 3621, not simply a “five-lever Chubb”. The standard number is stamped on the lock’s faceplate.
- Chubb stamped a serial number on every lock from 1819 until 1936, and the surviving registers can date a lock, often to the month.
- Lost the key to an old Chubb safe? Call a qualified safe engineer, have the lock number and proof of ownership ready, and never post a photo of a working key online.
In This Article
The Chubb key at a glance
| What it is | The key to a lever (tumbler) lock: a shank, a bow to hold it by and a stepped bit |
| Named after | Chubb & Son, makers of the detector lock patented by Jeremiah Chubb on 3 February 1818 |
| Everyday British use | Any lever mortice deadlock and its key, whoever made it |
| Standard insurers cite | BS 3621 (current edition BS 3621:2017) |
| Lock numbers | On every Chubb lock from 1819 to 1936, on the bolt head, a plate or the forend |
| Chubb locks today | ASSA ABLOY since 2000; sold as Union and Yale since 2010 |
| Chubb safes today | Chubbsafes, made by Gunnebo Safe Storage under licence |
| Lost safe key | A qualified safe engineer, with the lock number and proof of ownership |
What is a Chubb key?
Strictly, a Chubb key is a key made by Chubb for a Chubb lock. Collins’ dictionary gives “Chubb” as a British word for a type of patent lock whose bolt is set fast if someone tries to pick it: the detector lock.1
In practice the name covers much more. A London locksmith puts it simply: the “Chubb” is the colloquial British term for a lever mortice deadlock, and whether ERA, Yale, Union or another firm made it, in the UK it is a “Chubb”.2 Another compares it to calling every vacuum cleaner a Hoover or every ballpoint a Biro, and adds that not all mortice locks are Chubbs.3
Pick one up and it’s easy to recognise. It has a round shank and a short, flag-shaped bit cut into steps, so that its outline looks a little like the battlements of a castle.2 Each step lifts one lever inside the lock.4
Why Britain calls every lever lock a “Chubb”
The short answer is fame. Chubb made locks for house and office doors as well as for safes and banks, and the Chubb Archive dates the 3G110 “Castle” deadlock of its Security Range to 1960.5 Locksmiths explain the habit simply: Chubb was the best-known make of mortice lock in Britain, so its name stuck to the whole type.6
The name has since left the door-lock trade. In 2000 Williams Holdings sold the Chubb lock business, together with Yale and Union, to ASSA ABLOY, while the safe and strongroom side went to the Swedish group Gunnebo.7 When the Chubb Locks brand licence expired in 2010, ASSA ABLOY didn’t renew it, and the same locks have been sold as Union and Yale ever since.8 Union itself was an old Willenhall name: Josiah Parkes & Sons of the Union Works made Union locks and was bought by the Chubb Group in 1965.9
“Five-lever Chubb” and BS 3621: what insurers mean
Home insurance forms in Britain often ask whether the front and back doors have a “five-lever mortice deadlock”. The wording that matters is usually BS 3621, the British Standard for thief-resistant locks. Union, which now makes the former Chubb range, says insurers specify locks tested to BS 3621 to comply with their cover, and an insurance comparison site says most UK home insurers require a BS 3621 mortice deadlock on front and back doors.1011 The current edition is BS 3621:2017.12
- Look at the faceplate (the metal strip on the door edge). A conforming lock carries the British Standard Kitemark and the text “BS 3621”, and the maker’s name or product code.11
- Check the year after the number. “BS3621:1998” means the lock met the 1998 edition. Some insurers stipulate which edition they accept.3
- “Chubb” on an old lock is not enough. Locksmiths often find old locks with no British Standard mark, which are unlikely to meet an insurer’s requirement.3 If yours has no mark, ask your insurer what they accept before you claim, not after.
How a lever lock and the detector work
Inside a lever lock, a stack of flat levers sits over the bolt, each pressed down by a spring. Every lever has a slot, the gating, cut at a different height, and a post on the bolt can only pass when all the slots line up. Turning the key lifts each lever by exactly the right amount, then the last step of the bit throws the bolt.4
Since Robert Barron’s patent of 1778, a lever lifted too far blocks the bolt just as surely as one not lifted far enough. Jeremiah Chubb added the detector in 1818, and the story of how locks developed from there is told in our history of safe lock mechanisms.4
Levers
One step per lever
By 1851 the standard Chubb lock had six levers, so its key had six lifting steps plus one for the bolt.4
Detector
A lock that tells tales
If a wrong key lifts a lever too high, a detector catches it and the true key won’t open the lock until it’s reset.13
Curtain
A closing keyhole
Later locks added a rotating curtain that shuts the keyhole once a key is turned, so nothing else can be pushed in beside it.4
The detector was a kind of silent alarm. Its job was to warn the owner: when the proper key suddenly wouldn’t turn, they knew someone had tried the lock. The full story of the 1818 patent, the convict who failed to pick it and A. C. Hobbs, who succeeded in 1851, is in our article on the Chubb detector lock.
Did you know?
In 1875 Chubb still made its locks by hand so that each would differ from the next. George Hayter Chubb wrote that the hard part was making several locks alike, “for a touch of the file will completely alter a lock”.14
What old Chubb safe keys look like
A Victorian Chubb safe key is a larger, heavier version of the same idea: a steel shank, an oval or round bow, and a bit cut in steps for the levers. The woodcut above, from about 1850, shows the two kinds of lettering you may find on the bow: the firm’s London address, or simply “Chubb’s Patent”.
- “57 St Paul’s Churchyard” on a key or lock points to 1820–1877, when that was Chubb’s London office; “128 Queen Victoria Street” means 1877 or later.7
- Keyed alike. Every Chubb lock was meant to differ, but the firm could make several to one key when a customer asked,14 and the Chubb Archive shows pieces of furniture fitted with consecutively numbered, keyed-alike Chubb locks made in 1856 and 1887.15
- Master keys. Big installations were master-keyed. G. H. Chubb described a series of 1,100 locks for the Westminster Bridewell with master, sub-master and warders’ keys, in which only the Governor’s key could reset a detector.14
Safe locks had to resist more than picking. In 1875 G. H. Chubb said a safe lock must be strong, shielded by hard steel against drills, gunpowder-proof and simple enough never to go wrong; his firm’s gunpowder-proof lock is shown here. He added that neither Chubb nor the other large makers supplied safe locks for anyone else’s safes, and that Chubb had brought nearly a dozen lawsuits against dealers passing off cheap safes as “Chubb’s patent”.14 For all that armour, the key still worked on the same lever principle as a door key.
If you have a key but no safe, or a safe with an unmarked key, the bow lettering and the shape of the bit help a collector or engineer say what it is. Our guide to dating Chubb safes covers plates, addresses and models in more detail.
Lock numbers: dating a Chubb lock or key
When Chubb began making locks at Temple Street, Wolverhampton, in 1819, it stamped a serial number on every one, which is good news if you’re trying to date a lock now. The preferred place was the bolt head; some locks had it on a plate fixed to the case, and small locks on the forend. Towards the end of the 19th century Chubb offered “Best” and “Medium” quality versions of some locks, and from then on only the best quality was numbered. Numbering stopped altogether in 1936.16 Later locks may carry a customer’s numbering or an ID code instead.5
The numbers were written into lock registers, and those registers are the best dating tool there is. Sample entries from the Chubb Archive’s online registers give a feel for the sequence:17
| 452 | December 1819 |
| 37926 | November 1838 |
| 220073 | May 1850 |
| 617128 | July 1870 |
| 1168109 | March 1889 |
| 1619807 | October 1909 |
| 1833986 | July 1928 |
- Ask the Chubb Archive. Its curator offers to look up a specific lock in the records and give its date. Because many old locks are still in use, the Archive only publishes details of a lock with its owner’s permission.17
- The original registers survive at The London Archives (reference CLC/B/002), which describes them as particularly valuable for dating locks and safes.18 The registers for July 1828 to August 1836 were destroyed when Chubb’s London head office was bombed in the Blitz.16
- Lock date is not always safe date. Locks were made in batches and sometimes replaced, so treat the lock’s year as the earliest likely date for the safe.
Not sure what you have? Send us photos of the maker’s plate, the lock case and its number, with the size of the safe, and we’ll help you date it. There’s no need to photograph the key’s bit: the number and the plate tell us more.
Replacement keys for an old Chubb safe
There’s no central Chubb key service for antique safes, I’m afraid. The firm that made your safe has been split up and sold several times over, and its successors deal with modern products:
- Chubbsafes is the safe brand. Gunnebo bought Chubb’s safe business in 2000, and Chubbsafes are now sold by Gunnebo Safe Storage under licence from Chubb plc, which owns the name.719 Its customer support is the place to ask about a modern Chubbsafes model.
- Union and Yale, both ASSA ABLOY brands, make the former Chubb door lock range.8 They are relevant if your “Chubb key” is for a house door rather than a safe.
- A qualified safe engineer is the usual answer for a Victorian or early 20th-century Chubb safe. Look for members of a trade body such as the Master Locksmiths Association in the UK, the Safe & Vault Technicians Association or the Master Locksmiths Association of Australasia.20 Some specialists can also research discontinued safes, sometimes for a small fee.21
Our guide to replacement keys for old safes covers other makers too: what kind of key a safe takes, who can make one and what it costs.
What to have ready
- The lock number, from the bolt head, lock plate or forend, and any number on the old key’s bow.16
- The plate wording: name, address and any royal arms.
- Whether the safe is locked or open. An open safe with no key is a simpler job than a locked one.
- Proof that the safe is yours, such as house purchase papers or the will that left it to you. A reputable engineer will ask.
- Its size and where it stands, in case the engineer needs to work on site.
What it costs. We haven’t found a reliable published price list for keys to antique safe locks, so we won’t guess at one. The price depends mainly on whether the safe is locked, whether the engineer has to come to you, and whether they make a key for the old lock or advise fitting a new one. Ask for a written quote before work starts.
Never post a photo of your key
It’s tempting to put a picture of an old key on a forum or a sale listing, especially a handsome Victorian one. Don’t, if the key still works a lock you use. In 2008 computer scientists at the University of California San Diego showed that ordinary house keys could be copied from photographs: their software decoded keys from an image taken about 195 feet away, and they warned that photo-sharing sites were full of usable key pictures.22
“Keep it in your pocket unless you need to use it.”
Professor Stefan Savage, UC San Diego, on keys, 2008
Lever keys are no exception. The safe historian behind safeman.org.uk records cases where keys were photographed with long-focus lenses as they went into the keyhole; one was a Chubb 3G110 mortice key on a door that also controlled an alarm system. The same page describes a seven-lever key memorised by eye while it lay on a desk, well enough for a skilled locksmith to make a working copy.23
The Victorians knew this too. G. H. Chubb blamed the Great Gold Robbery of 1855 on the South-Eastern Railway on thieves who had the keys in their hands for only moments, just long enough to take impressions of them.14 If you need to show someone your key, show the bow and the number, not the bit.
Lost the key, or the key won’t turn?
- Don’t drill or force it. Ireland’s Health and Safety Authority notes that most safes with mechanical locks can be opened by an expert without drilling, and drilling an old safe can also release asbestos.24
- Key turns but won’t unlock? On a Chubb detector lock the detector may have been tripped, perhaps by a worn key. Chubb’s own instruction was to turn the true key the locking way first, then unlock as normal.13 If that doesn’t work, stop and call an engineer.
- Locked with no key at all? Our step-by-step guide, locked out of an old safe, explains what to do and whom to call.
Did you know?
In 1875 G. H. Chubb recommended a numbered label on the key ring, engraved with an address but not the owner’s name. A finder returned the keys to that address, the owner was traced through a register, and the finder never learned whose keys they were. He reported several thousand in use and keys coming back “almost daily”.14
Chubb key myths
A “Chubb lock” was made by Chubb.
In British usage it means any lever mortice deadlock, whether ERA, Yale, Union or another firm made it.
Any five-lever Chubb satisfies the insurer.
Insurers usually want BS 3621. Look for the Kitemark and “BS 3621” on the faceplate.
Chubb still makes door locks.
The lock business went to ASSA ABLOY in 2000, and the range has been sold as Union and Yale since 2010.
A photo of a key is harmless.
Researchers decoded keys from photos taken about 195 feet away in 2008.
A lost safe key means drilling the door.
Most mechanical locks can be opened by an expert without drilling.
Frequently asked questions
What is a Chubb key?
The key to a lever lock: a round shank with a stepped, flag-shaped bit, one step per lever. Strictly it means a key made by Chubb, but in Britain it’s used for any lever mortice deadlock key.
Is a “Chubbs key” the same thing?
Yes, spell it however you like. “Chubbs key”, “Chubb’s key” and “Chubb key” all mean the same lever-lock key; the firm’s own locks and keys were often marked “Chubb’s Patent”.
What is a Chubb lock?
Originally the detector lock patented by Jeremiah Chubb in 1818. Today the name is used in Britain for any lever mortice deadlock, and the former Chubb range is sold as Union and Yale.
How do I get a replacement key for an old Chubb safe?
Call a qualified safe engineer with the lock number, photos of the plate and proof that the safe is yours. For a modern Chubbsafes model, contact Chubbsafes customer support.
How old is my Chubb lock?
Find the serial number on the bolt head, lock plate or forend. Numbers up to 1936 can be dated from Chubb’s registers, and the Chubb Archive will look one up on request.
Is my Chubb lock BS 3621?
Only if the faceplate says so, with the Kitemark and “BS 3621”. An old Chubb with no British Standard mark probably won’t meet an insurer’s requirement.
Sources:
- Collins English Dictionary, Complete & Unabridged (2012 digital edition), “Chubb” (British), via Dictionary.com. ↩︎
- ADR Locksmith Services, Hackney, “What type of lock do I have? The Chubb lock”. ↩︎
- Millennium Locksmiths, “Mortice locks and mortice lock locksmiths”. ↩︎
- Charles Tomlinson (ed.), Rudimentary Treatise on the Construction of Locks, from the papers of A. C. Hobbs (1853), chapters on tumbler locks and Chubb’s locks, via Project Gutenberg. ↩︎
- The Chubb Archive, “Post 1936 locks” (entry: 3G110 Security Range “Castle” deadlock, 1960). ↩︎
- Mobile Locksmith Domestic and Auto, “Mortice locks (Chubb locks)”. ↩︎
- The Chubb Archive, “Early sales, offices, Chubb Group, 1980s and on”. ↩︎
- Wikipedia, “Chubb Locks”, citing SafeZone, “Why did Chubb Locks change their brand?” (2013); see also Barry Bros Security, “Chubb”. ↩︎
- Grace’s Guide, “Josiah Parkes and Sons” (Union Works, Willenhall; acquired by the Chubb Group in 1965). ↩︎
- Union (ASSA ABLOY), “BS 3621”, help and support: standards and legislation. ↩︎
- Quotezone, “How do I know if my lock is a 5 lever mortice deadlock?” (home insurance guide). ↩︎
- BSI Knowledge, BS 3621:2017, Lock assemblies operated by key from both the inside and outside of the door (published 30 June 2017). ↩︎
- The Chubb Archive, “The Chubb Detector”, quoting Chubb’s 1930 lock catalogue. ↩︎
- George Hayter Chubb, Protection from Fire and Thieves (London, 1875), ch. I (locks and keys) and ch. III (safes), via Project Gutenberg. ↩︎
- The Chubb Archive, “Lock Stories” (furniture fitted with keyed-alike Chubb locks of October 1856 and October 1887). ↩︎
- The Chubb Archive, “Jeremiah Chubb’s original patent lock serial numbers” and “Lock works registers”. ↩︎
- The Chubb Archive, “Registers” and the online lock registers 1819–1936 (entries by serial number and date). ↩︎
- AIM25 / The London Archives, “Chubb and Son Limited, locksmiths and safe manufacturers”, ref. CLC/B/002. ↩︎
- Chubbsafes, “About Chubbsafes” (trademark of Chubb plc used under licence; site published by Gunnebo Safe Storage AB), accessed October 2026. ↩︎
- Trade bodies: Master Locksmiths Association (UK), Safe & Vault Technicians Association (US and international), Master Locksmiths Association of Australasia. ↩︎
- Bradley’s Master Locksmiths, “Discontinued safes”. ↩︎
- University of California San Diego, Jacobs School of Engineering, “Keys can be copied from afar, Jacobs School computer scientists show” (news release, 30 October 2008), on B. Laxton, K. Wang and S. Savage, “Reconsidering physical key secrecy: teleduplication via optical decoding”, ACM CCS 2008, doi:10.1145/1455770.1455830. ↩︎
- safeman.org.uk, “Safe scrapbook” (section on compromised keys). ↩︎
- Health and Safety Authority (Ireland), “Asbestos risks in safes and fire resistant cabinets” (information note, updated September 2023). ↩︎
