A rare £2 coin, which could fetch as much as £500 at auction, could be sat in your change waiting to be found.

Experts are alerting Brits to the rare coin, which features an error making it a must have for collectors.

The £2 in question was released by the Royal Mint in 2014 to commemorate 100 years since the start of WW1.

The coin shows the face of the First World War Lord Kitchener who featured on the “Your Country Needs You” posters.

While a normal version of the coin will be worth no more than its face value of £2, a batch of the coins featured a rare error that boost their value for collectors.

On some of the coins the words “Two Pounds” are missing on the head side of the coin.

According to experts at Coin Hunter, 5,720,000 of these coins are still in circulation but it appears to be “very rare” to find one without a date.

It isn’t clear exactly how many of coins with an error remain in circulation but the first of its kind sold in March 2020 for £500.

Coin Hunter experts said on Facebook: "Check your coins that feature Lord Kitchener.

"If the heads side does not show 'TWO POUNDS' - you have an error that appears to be very rare."

What makes a coin valuable?

The 50 pence piece has become the most valued and collected coin in the UK, with many collectable designs appearing on its heptagonal canvas.

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Its 27.5mm diameter makes it the largest of any British coin, and allows space for decorative pictures. It has often been used to celebrate big events over the past 50 years of British history.

The rarest coins tend to be of the greatest value, with the mintage (number of coins with each design made) being the fundamental attraction for collectors.

Forestry Journal: The rarest coins minted during Queen Elizabeth II's reignThe rarest coins minted during Queen Elizabeth II's reign (Image: Royal Mint/PA)

Along with the design, other aspects of the coin which increase value are the condition of the coin and whether it has an error in its design.

The way in which it is sold can also determine the coin’s value - while some coin collectors will bid vast amounts of money on eBay or at auction, others opt for more robust valuations by selling via a coin dealer.

Royal Mint rarest coins from Queen Elizabeth II’s reign

Here is a list of rare coins compiled by the Royal Mint, with information about the year of release, denomination, design features and whether or not the coin is still in circulation:

  • 2019, 10p, a set of “A to Z” coins celebrating Britain. Letters Y, W and Z each had a mintage of 63,000, yes.
  • 2019, 10p, also from the A to Z collection, the letter R had a mintage of 64,000, yes.
  • 2019, 10p, all other letters in the A to Z collection had a mintage of 84,000, yes.
  • 1992-1993, 50p, the coin celebrated the UK’s presidency of the Council of Ministers and the completion of the European single market. The design included a representation of a table with 12 stars, linked by a network of lines and the mintage was 109,000. The Mint said this was the lowest number of its 50ps issued into circulation, no.
  • 2009, 50p, the design features the Kew Gardens pagoda with a decorative leafy climber twining in and around the tower, 210,000, yes.
  • 2018 dated, 10p, the A to Z 10p collection celebrating Britain, each letter in this year had a mintage of 220,000, yes.
  • 2015, £2, this coin paid tribute to the Royal Navy and its role during the First World War, and had a mintage of 650,000, yes.
  • 2015, £2, it featured Britannia for the first time on a circulating £2 coin, with a mintage of 650,000, yes.
  • 1985, 50p, the coin featured a figure of Britannia, with a shield, with a mintage of 682,103, no.
  • 2002, £2, four £2 coins celebrating each home nation for the Commonwealth Games. Mintage figures for Scotland were 771,750, for Wales, 588,500, for Ireland, 485,500, and for England 650,500, yes.
  • 2012, £2, the coin celebrated the closing of the 2012 Olympics and had a mintage of 845,000, yes
  • 2008, £2, the coin marked the centenary of the Olympic Games, with mintage of 910,000, yes.
  • 2008, £2, the coin marked the end of the Beijing 2008 Olympics, with a mintage of 918,000, yes.
  • 2011, £2, the coin commemorated 400 years since the King James Bible was published, with a mintage of 975,000, yes.
  • 2018, 50p, a series of coins celebrated Beatrix Potter’s classic tales, with a mintage of 1,400,000 each for the Peter Rabbit and Flopsy Bunny designs, yes.
  • 2011, 50p, a series of coins celebrating the London 2012 Olympics. Mintages included 1,454,000 for tennis, 1,161,500 for judo and 1,129,500 for wrestling, yes.
  • 2010-2011, £1, a series of round pound coins featuring official badges of capital cities in the UK. They had mintages of 935,000 for Edinburgh, 2,635,000 for London and 1,615,000 for Cardiff, no.
  • 2008, £1,  the round pound coin featured the UK’s Royal Arms, with a mintage of 3,910,000, no.