Britons are being encouraged to re-examine their everyday change after a rare error in the production of a 20p coin has led to a surge in collector interest. The misprint, which dates back to 2008, has turned an otherwise ordinary coin into a sought-after item potentially worth hundreds of times its face value.
The coin, released during a period of design transition at the Royal Mint, slipped into circulation without the usual date inscription — a mistake that has since become a point of intrigue in the numismatic world. While relatively few were minted, they remain legal tender and continue to appear in pockets and purses across the UK.
Minting Error From 2008 Leaves Coins Without a Date
A rare minting error involving the British 20p coin has resurfaced, with experts urging the public to examine their change for a potentially valuable find.
According to The Royal Mint, the anomaly occurred in 2008 during a transitional redesign of the coin, when the new reverse design featuring a portion of the Royal Shield was accidentally paired with the old obverse side bearing the Tudor rose.
As a result, a limited number of coins were released without a date on either side—an oversight known in numismatic terms as a “mule error.”
The Royal Mint confirmed that the issue affected fewer than 250,000 coins out of the 136 million 20p pieces minted between 2008 and 2009. Despite the error, these coins remain legal tender and are technically worth 20 pence.
However, their unusual nature has made them increasingly desirable among coin collectors. The value of an undated 20p coin in fair condition can now reach or exceed £60, depending on demand and condition.
Public Urged to Inspect Coins Amid Ongoing Discoveries
The advice to “stop spending your 20p coins without checking them first” was recently shared by a numismatic expert known as the Coin Collecting Wizard. Speaking via social media, the expert highlighted the fact that despite their rarity, these undated coins are still being found in general circulation.
“Normally, 20p coins have the date on the back, but if you check and there’s no date on either side, you might be holding the rare one.” he explained.
While not considered extremely rare within professional numismatic circles, the undated 20p has gained popularity due to its visibility and the ease with which it can be identified.
The expert further clarified that the mistake was the result of mismatched dies used during the transition to a new coin design—a process that evidently bypassed quality control measures at the time.
The Royal Mint has not issued any new guidance on the coins, maintaining their legal tender status. Collectors and members of the public interested in verifying a coin’s authenticity are encouraged to consult with reputable dealers or professional valuation services.
