The Kew Gardens 50p coin was once the UK's rarest - but now there's a new king of the castle

The Royal Mint has revealed the most valuable 50p coins in its collection. Until recently, the Kew Gardens 50p coin was the rarest of its kind in circulation in the UK.

The 50p coin was released in 2009 to mark 250 years since the opening of Kew Gardens.

It shows the Chinese Pagoda at the Royal Botanic Gardens on the tails side and a portrait of Queen Elizabeth II as its head.

Around 210,000 copies of the coin were produced by The Royal Mint.

After being listed on eBay, the 50p coin attracted 20 bids before selling for £139.

The 50 pence piece has become the most valued and collected coin in the UK.

Its larger 27.5mm diameter allows more space for the team to create special illustrations.

The rarest coins tend to be the most valuable, with the mintage (number of coins with each design made) also playing a key part in how much collectors will pay.

Its condition is also important - so collectors keep rare coins safe from damage.

The Royal Mint has revealed the most valuable 50p coins in its collection.

Until recently, the Kew Gardens 50p coin was the rarest of its kind in circulation in the UK.

A 50p depicting the Atlantic Salmon and bearing the King’s portrait is now the rarest 50p coin in circulation, the Royal Mint has confirmed.

Just 200,000 of the Atlantic Salmon 50ps have been released to UK banks and post offices, 10,000 less than the 2009 Kew Gardens coin.