Tiny overlooked error on your 20p could make it worth 230 times its face value

A RARE 20p coin with a tiny error has just sold for over 230 times its face value – and you could have one sitting in your change without even knowing.
An undated 20p coin went under the hammer on eBay for a whopping £49.04.
The coin, which attracted seven bids, is part of the Royal Mint’s famous error series – and collectors are desperate to get their hands on one.
The Royal Mint, the official maker of British coins, regularly puts limited edition pieces into general circulation.
Minted in 2008, this particular 20p is missing one key detail – the date.
Normally, all British coins feature the year they were produced. But in a rare mix-up at the Royal Mint, a small number of these 20p coins were released without any date at all.
That tiny error has made them incredibly valuable to collectors, who love rare and unusual pieces.
One lucky seller recently flogged a similar undated 20p at the RWB Auction’s February 2025 sale for an eye-watering £70 – 350 times its face value.
Meanwhile, one of the most popular types of coins to collect are 50p piece.
This is because of their large surface area, as there is enough space to add new and intricate designs.
A 2019 Kew Gardens 50p went under the hammer on eBay for a whopping £122.09 - 244 times its face value.
The coin, which attracted 13 bids, is one of the most sought-after pieces among coin collectors.
In some cases, extremely rare 50p pieces have sold for a whopping £950
Collectors are urged to check their spare change carefully – as spotting this tiny error could mean a tidy profit.
Look closely at both sides of the 20p coin – if you can’t find a date anywhere, you might just be holding a valuable Royal Mint blunder.
Coin mistakes like this are highly sought after by numismatists and can often fetch big money online or at auction.
If you think you’ve got one, it’s worth getting it checked out or listing it on eBay to see what it could fetch.
Some of the rarest coins in circulation can sell for hundreds – even thousands – of pounds.
As mentioned earlier, the large diameter makes 50p pieces one of the most popular types of coins to collect.
With a 27.5mm diameter, it's the biggest British coin and is used to celebrate big occasions, anniversaries, and historical events.
Over the Olympics a range of themed 50p coins were printed, with the Aquatics 50p reaching up to an eye-watering £2,000 in auction.
This coin soared in price due to an initial design error, which was quickly corrected, leading to very few misprints in circulation.
Errors make a coin unique which means they will most likely be worth more, as there a fewer of them.
Even without a misprint, if a coin has a low mintage there are fewer of them in circulation and so are deemed rare.
As a general rule of thumb, the rarer the coin the more valuable they are to collectors.
If you have managed to get your hands on a rare coin, there are a few ways you can go about selling it.
Online platforms like eBay, Facebook marketplace, or trading apps can be easy to use - but there are risks.
Scammers may try and target sellers with this trick - they'll say they are keen to purchase the item and ask for money upfront for a courier.
They have no plan on collecting the item and are only using the courier to grab free cash.
When buying or selling on Facebook Marketplace it's advisable to meet up in person - make sure this is a safe space and avoid payment links.
Many sellers will choose to handle cash when meeting to limit the risk of scams.
To ensure the ultimate safety you can sell rare coins at an auction.
This can be done through The Royal Mint's Collectors Service which has a team of experts who can help you authenticate and value your coin.
Finally, you can sell rare coins on eBay.
COMMENTS by Consumer Editor, Alice Grahns:
It’s easy to check if items in your attic are valuable.
As a first step, go on eBay to check what other similar pieces, if not the same, have sold for recently.
Simply search for your item, filter by “sold listings” and toggle by the highest value.
This will give you an idea of how much others are willing to pay for it.
The method can be used for everything ranging from rare coins and notes to stamps, old toys, books and vinyl records - just to mention a few examples.
For coins, online tools from change experts like Coin Hunter are also helpful to see how much it could be worth.
Plus, you can refer to Change Checker’s latest scarcity index update to see which coins are topping the charts.
For especially valuable items, you may want to enlist the help of experts or auction houses.
Do your research first though and be aware of any fees for evaluating your stuff.
As a rule of thumb, rarity and condition are key factors in determining the value of any item.
You’re never guaranteed to make a mint, however.
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