Believe it or not, there are millions of notes and coins in circulation right now that are worth far more than their face value. We've rounded up some of the most valuable UK currencies, from the Kew Gardens 50p to some very rare new £5 notes. But please make sure you do your research before shelling out for any of these to avoid getting conned.

 

This 50p was created to mark the 2012 London Olympics. For those of us that still can't get our head around the 'Offside Rule', here's a coin to do it for you! This piece of silver will commonly make you £10.

To celebrate the British presidency of the council of Europe in 1992, the Royal Mint issued a commemorative 50p coin. Only 109,000 coins were issued but you won't find them in circulation because the 50p was made smaller in 1997. But check your home and pockets, because if you find an old one it could be worth £20.

Only 485,500 of these special edition Commonwealth Games Northern Ireland £2 coins were minted – a relatively tiny run in coinage terms. As a result, each one can fetch £25 or more these days.

The rarest sterling coin in circulation, the 2008 Kew Gardens 50p piece had a limited run of just 210,000. The shiniest, most pristine examples can command prices up to £120, so keep a keen eye out for these coins.

Thousands of undated 20p pieces fell through the net in 2008 following a mistake in the minting process. Be sure to check your change because these dateless coins go for up to £200 each on eBay.

This cute, special-edition WWF 50p design was released in 2011. The centre features the famous panda logo and is covered with 50 other animals including, lions polar bears, sharks and dolphins. It's no wonder this coin is popular among collectors and usually sells for £200 plus.

All twopences featured the words 'New Pence' up to 1981 and 'Two Pence' thereafter. However, a batch in 1983 was accidentally minted with the 'New Pence' lettering. These coins are worth up to £700 each.

In 2012, the Royal Mint released a 50p piece to commemorate aquatic sports at the London Olympics. The original design (pictured on the left) showed the swimmer with water obscuring the face. This was tweaked to make the face more visible (pictured on the right) but not before 600 coins with the original design were released. These rare coins are now worth up to £3,000 each.

And the latest rare coins to be uncovered are the 2015 Britannia £2 coins, with around 1 in 200 struck showing the Queen's effigy upside down! According to experts at website Change Checker this means fewer than 3,500 coins are floating around waiting to be found. It's not certain how much the coins will sell for yet, but it's likely to be more than face value. Keep your eyes peeled!

To celebrate what would have been Beatrice Potter's 150th year, the Royal Mint released three collections of five Peter Rabbit-themed 50p coins. There is one set of five coins in general circulation, with complete sets going for around £30 online. A sealed collection of the five coins is now sold out but fetching around £50 on eBay. The third set is a special edition of the coins which were coloured in. These are sold out on the Royal Mint website and selling for as much as £100 each online.

The new polymer £5 note was introduced into circulation in September 2016. Polymer banknotes are more durable than paper banknotes, not to mention cleaner and more secure, which only adds to their appeal. The Bank of England plans to replace all £5, £10 and £20 paper notes for polymer noted by 2020. As these new notes hit the streets, some unique serial numbers emerge. And some are worth quite a bit...

Fivers with AA01 serial numbers are the closest produced to the first banknote, which made them valuable to collectors. And if the 'AA01' prefix is followed by a very low serial number, it's even more sought after. But we can't all have a piece of the pie, as the Bank of England kept the first few polymer £5 banknotes for auction. The bank put note number AA01 000017 under the hammer in October 2016 where it sold for £4,150, which went to charity.

Much was made about notes with interesting serial numbers, and indeed, the AK47 series do fetch a bit of cash online. However, reports of these notes going for thousands of pounds are greatly exaggerated. They are going for between £5 and £7 on eBay, with more interesting serial numbers like AK47 007 fetching higher values. 

The new £10 featuring Jane Austen has also proved popular with collectors. As usual, look out for low serial number notes, specifically those starting with AA001 followed by a very low number sequence afterwards. Of course, most of the really low sequence notes have already been snapped up.

A quick search of eBay shows there are various AA001 notes with non-descript serial numbers thereafter selling for around £15, so you're really looking for additional quirks to boost the value. For example, serial numbers that look like dates such as Austen's birthday (16 121775), death day (18 071817) or date of her books' publication (28 011813 for Pride and Prejudice and so on).