UK Coin Errors List 2026: Complete Guide to British Minting Mistakes
A handful of UK coins left the Royal Mint with mistakes that escaped quality control. Some are worth a few extra pounds. Others — like the 1983 "New Pence" 2p — multiply face value 15,000 times. Here's every major British coin error you can realistically hope to find.
What counts as a mint error
A genuine mint error happens at the Royal Mint — before the coin ever reaches circulation. Post-mint scratches, gouges, or amateur alterations don't count and have no numismatic value. The three big categories are:
- Die errors — wrong, cracked, clashed or rotated dies produce characteristic design anomalies on the finished coin.
- Strike errors — off-centre strikes, double-strikes, weak-strikes, missing elements.
- Planchet errors — blanks of the wrong metal, size or thickness accidentally fed into the wrong press.
The top 10 circulating UK coin errors
| # | Error | Year(s) | Category | Typical value |
|---|---|---|---|---|
| 1 | "New Pence" 2p mule | 1983 | Die mule | £300 – £700 |
| 2 | Undated 20p ("dateless mule") | 2008 | Die mule | £50 – £200 |
| 3 | Inverted effigy £2 | Various | Die rotation | £80 – £150 |
| 4 | "Silver" 2p (cupronickel 2p) | Rare pre-1992 | Wrong planchet | £300 – £800 |
| 5 | Off-centre strike 50p | Various | Strike error | £30 – £100 |
| 6 | Missing edge inscription £2 | Various | Strike error | £25 – £80 |
| 7 | Blank planchet (cupronickel) | Various | Never struck | £15 – £50 |
| 8 | Bronze 2p missing design elements | Various | Die clash | £10 – £30 |
| 9 | Overdate (e.g. "8 over 7") | Pre-1970 | Die repunch | Varies |
| 10 | Brockage (reverse mirror) | Various | Stuck coin | £40 – £120 |
1. The 1983 "New Pence" 2p mule
All UK decimal coins were inscribed "NEW PENCE" from 1971–1981. The inscription was updated to "TWO PENCE" from 1982. But during 1983 a batch of Royal Mint proof coins was struck using the obsolete "NEW PENCE" reverse die — fewer than 1,000 escaped into private hands. These are the single most valuable modern British coin errors.
To check: flip any 1983 2p over. If it reads "TWO PENCE" under the shield, it's a normal coin. If it reads "NEW PENCE", congratulations — it's worth £300–£700. See our 2p coin values guide for full details.
2. The 2008 "Undated" 20p
When the Royal Mint redesigned the 20p in 2008, moving the date from the reverse to the obverse, a small batch was struck using the old obverse die (no date on the obverse) paired with the new reverse die (no date on the reverse). Result: a coin with no date on either side — the first dateless UK coin in 300 years.
Identification: hold the coin with the royal shield uppermost. Check for a date beneath the shield and then on the portrait side beneath the monarch. If there's no date anywhere, you have the mule. Between 50,000 and 200,000 entered circulation. See our 20p coin values guide.
3. Inverted-effigy £2 coins
When the obverse (portrait) and reverse designs are struck 180° out of rotation, you get an "inverted effigy". Hold a normal £2 portrait-up, flip vertically: the reverse should read right-way-up. On an inverted-effigy example it will be upside down. Most-reported on Queen Elizabeth II £2s but possible on any British coin. Authentic examples trade £80–£150 at Noonans auctions.
How to get an error coin authenticated
For any suspected error worth £50+:
- Photograph both sides at high resolution on a neutral background.
- Weigh and measure — compare to Royal Mint specifications (published per denomination).
- Send for grading to NGC UK or PCGS. Fees typically £25–£50 per coin.
- For high-value pieces, consign to Baldwin's or Spink with the authentication certificate.
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