If you're hoping to make a small fortune from the coins lurking under sofa cushions or in the bottom of jacket pockets, then there's good news and there's bad news. The good news is that there are some astonishingly valuable coins out there, just lurking in people's houses. The bad news is that if you want something that's worth thousands - or even millions of pounds - you'll need something pretty old.
GoCompare has worked with antique coin traders, Chards, to produce a list of the most expensive coins on the planet right now, and the newest coin featured in the top ten comes from 1957.
Check out the full list here (article continues below)
See also: Is your £1 worth £30?
See also: Is your £2 coin worth more than £300?
See also: 10 surprisingly valuable coins in your wallet: the ones you don't know about
The really valuable ones tend to be ones struck in very low numbers in the early part of the 20th century, usually in gold. The really desirable ones tend to have a quirk in their history - such as the two that were recalled to be exchanged for paper money, the many that were melted down during the war, and the coins that only got produced in small numbers before the king abdicated.
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There is, however, some hope for anyone who dreams of finding something valuable lurking among their change. The GoCompare study highlighted some valuable coins minted since 1980, which are worth checking your pockets and sofa cushions for.
Many of them are the gold and silver proofs struck for dignitaries, which have never made it into circulation. However, aside from these you may still find seven of them kicking around at home:
1. 1983 2p piece - marked as new pence rather than two pence by mistake and thought to be worth £1,350.
2. 2012 50p piece - released to commemorate swimming in the Olympics, with a swimmer on the reverse. The valuable ones have the swimmer's face underwater, which was quickly altered for subsequent issues. The originals are worth £750.
3. 2014 50p featuring Britannia - some of these were printed with the wrong reverse side (they were meant for the Year of the Horse commemorative coins). They are worth £350.
4. 2014 50p commemorating the Year of the Horse - some of these have the reverse that was intended for the Britannia coin and are worth £350.
5. 2008 undated 20p piece - this happened when the side that the date was printed on was switched, and a number accidentally featured no date. The coins are worth £100.
6. 1992-1993 Council of European Community 50p. These were minted in very small numbers and so are worth £35.
7. 2009 Kew Gardens 50p. Perhaps the most famous valuable 50p, worth £30 because of its rarity.