Reference

UK Coin Error Catalogue

Every type of British coin error explained — what it is, how it happens, how to spot it, how to authenticate it, and what it's worth. Each entry covers a single error category with UK-specific examples and realised auction prices.

Mule
Mismatched obverse / reverse
Off-centre strike
Design shifted to one side
Double-die (doubled die)
Doubled image from die hubbing
Brockage
Mirror image from a stuck coin
Lamination
Surface metal layer peels
Clipped planchet
Curved bite from punching error
Wrong planchet (off-metal)
Struck on wrong-denomination blank
Die crack
Raised line from die fracture
Die cud
Major die break — featureless blob
Rotated die
Reverse rotated relative to obverse
Broadstruck
Struck without retaining collar
Missing edge inscription
No edge text or milling
Filled die
Missing letters or numbers

Why error coins are valuable

Royal Mint quality control catches the vast majority of strike errors before coins leave the mint, so any error coin in circulation represents a process failure that slipped through. Combined with collector demand, this scarcity means a £2 coin with a missing edge inscription can sell for 100× face value, and a 50p struck on the wrong planchet can clear £1,500. Larger denominations and bimetal coins (£2) typically command higher premiums than 1p or 2p errors of equivalent severity.

Counterfeits and post-mint damage are the biggest risks when buying errors. PCGS, NGC and CGS UK certification is the gold standard for any error coin worth over £200. For lower-value examples, the identification checklists on each error page below help separate genuine errors from kitchen-table fakes.

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