Check your change! 50p coin worth £24

The Royal Mint says the coin is likely to disappear fast now that it has been declared the rarest in general circulation.

A 50p coin produced just five years ago has shot to rarity value, with the Royal Mint urging the public to check their change and dealers on eBay asking as much as £24 for the Kew Gardens coin issued in 2009.

Just 210,000 of the coins were minted to mark the 250th anniversary of the Royal Botanic Gardens, compared with 22.7m with the shield of the Royal Arms in 2008 and 7.5m of the Girlguiding 50p in 2010.

Around one in every 300 people is likely to have a Kew Gardens 50p, but the Royal Mint said it was likely to disappear fast now that it had declared the coin as the rarest in general circulation.

A spokesman said: "We're urging everyone to check their change to see whether they could have one of these exceptional coins in their pockets."

The coin featuresthe Royal Botanic Gardens pagoda encircled by a vine, the dates 1759 and 2009, and the word Kew at the base of the pagoda.

There are numerous bids for the coin on eBay, with Buy it Now dealers asking up to £23.95. The London Coin Company is asking £54.95 for an uncirculated example in its original sealed plastic case.

Other Royal Mint commemoratives are unlikely to see such a hike in value, given the vast numbers of coins produced. A spokesman for the numismatic dealer Spink and Co said the 50p coin struck to commemorate the 2012 Olympics was still worth just 50p.