Do you have this valuable 50p coin in your change?

It's time to check the coins in your pocket, because the experts say a previously unnoticed 50p could be worth far more than its face value. The coin in question features Jemima Puddle-Duck, and was released last year to celebrate the 150th year since Beatrix Potter's birth. If you have one in your change, it could be worth more than 17 times its face value.

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The 50p was part of a special edition set - which also featured Peter Rabbit, Squirrel Nutkin, and Mrs Tiggy-Winkle. They were always going to appeal to collectors - because of the enormous appeal of the characters, and the popularity of collecting complete sets.

Figures from the Royal Mint reveal that Jemima Puddle-Duck will particularly appeal, because it was released in smaller numbers than any of the others. Only 2.1 million of these coins were released into circulation. Compare that to the 9.6 million Peter Rabbit coins released and 5 million Squirrel Nutkins. For those who want the complete set, therefore, the Jemima Puddle-Duck coin will prove the trickiest to track down - and therefore the most valuable.

In fact, Jemima Puddle-Duck is the 8th rarest 50p in circulation.

What's it worth?

The experts are already reporting interest from collectors. ChangeChecker arranges coins swaps between collectors, and already has eight times as many people looking for the coin than collectors who have one available to exchange. eBay sales, meanwhile, are hotting up, and the coins are already selling for £5-£10 each. Coin dealers are selling uncirculated versions for £10.

It's not exactly money to retire on, but it's a decent sum for a 50p coin - and this could be just the start. With coins in demand like this, as time goes on, more and more of them are withdrawn from circulation by collectors. It means that the remaining ones fetch higher and higher prices.

For the right coin, prices can reach astronomical heights. According to ChangeChecker, the rarest 50p is the Kew Gardens coin, which is valued at around £80. This is followed by six 50ps commemorating the 2012 Olympics: one explaining the offside rule, the triathlon coin, the judo one, the wrestling one, tennis and goalball - all of which can sell for up to £10.

It's not just the rarity that matters either. When a coin is in particular demand, the price can be astronomical, and Jemima Puddle-Duck has two things going for it in this regard. First, the cutesy appeal and the popularity of the author means the coins may be collected by people who wouldn't normally consider coin collecting. Add to that the fact that collectors love to chase down a full set of a special edition coins, and we could see the price of this coin go even higher.

All of which means it might be worth digging around in your change to see if you have one of these coins, and then keeping an eye on prices.