Every keen collector knows that it is worthwhile paying close attention to the small details of your coins – it’s the only way you can ever hope to spot an error. However, it’s also important to know when you have a genuine rarity.

There are a few stories that crop up more often than others, so today I’d like to help dispel some of the myths about UK coins.


2016 £2 coins edge inscription mix up

In 2020, a small collection of the 2016 Shakespeare Tragedy £2 coins were found with the wrong edge inscription on them. A mix up of blanks led to some of the Shakespeare Tragedy £2 coins being struck with the edge inscription of the First World War Army £2, which was issued in the same year.

2016 £2 coins edge inscription mix-up

‘Errors’ like these can occur when blanks get mixed up or aren’t properly changed over when striking a new batch of coins.

This type of miss-strike isn’t very common but it can happen when coins are struck in the same year, like the 2013 London Underground £2 coins, where some were found with the incorrect edge inscriptions!

One of a kind 20p struck on a 1p blank

In 2018, the news broke of a one of a kind coin purchased on eBay for just £50 now being valued at over £2,000!

20p coin struck on a 1p blank. Credit: Alun Barker/SWNS

This unique 20p coin struck onto a 1p blank has been verified by The Royal Mint as a genuine coin and was also sent to ANACS (America’s oldest coin authentication and grading service) and confirmed to contain a mix of foreign metals to form a copper plated steel blank. 

It’s the first of its kind seen by ANACS and experts have suggested it would fetch a minimum of £2,200 at auction.

The undated 20p

It’s regarded by many as the Holy Grail of change collecting, and back in 2008, the undated 20p saga encouraged an entire country to start carefully checking their coins. In fact plenty of collectors are still doing just that in the hope of finding one.

The 2008 Undated 20p

In 2008, the reverse of each denomination from 1p to £1 was redesigned by Matthew Dent and so The Royal Mint produced a new die with the date on the obverse. 

However, when the new Royal Shield 20p coins were struck for circulation, the old die was accidentally used. The Royal Mint confirmed that a batch of no more than 250,000 were issued with no date on either side of the coin.

The 2014 Year of the Horse ‘Mule’ Coin

A “mule” is a coin where one of the sides has been struck with the wrong die.  And that’s what happened with some of The Royal Mint’s 2014 Year of the Horse coins.

The 2014 ‘Mule’ Year of the Horse 1oz Silver Coin

The Royal Mint acknowledged the error, which resulted in approximately 17,000 Britannia coins being struck with the non-denticled Year of the Horse obverse and 38,000 Year of the Horse coins with the denticled Britannia version as their obverse. At the time listings on eBay were as high as £500.

The ‘Silver’ 2p striking error

The 2015 dated ‘Silver’ 2 pence coin was dropped into a Royal British Legion collection tin in Wiltshire a few weeks ago and made headline news nationwide.

The 2015 Rare 'Silver' 2p
The 2015 Rare ‘Silver’ 2p

The coin was confirmed as an extremely sought-after minting error after a 10p ‘blank’ found its way into the presses and a 2p was accidentally struck onto it. 

Errors like this are extremely rare, but The Royal Mint verified the authenticity of the coin. There has only ever been one other ‘silver’ 2p which sold in 2014 for £1,357.

The Inverted Effigy £2

In 2015, a small number of “Inverted Effigy” £2 Coins entered circulation with the Queen’s head rotated clockwise by approximately 150 degrees.

britannia 2 pound coin error2 0031 - Just Discovered: Rare “Inverted Effigy” £2 Coin

First discovered by a Change Checker, and later confirmed as genuine by The Royal Mint, this unusual strike appears on a handful of the 2015 Britannia £2 Coins.

The Royal Mint has accounted for the seemingly impossible misalignment of the Queen’s effigy as almost certainly the result of one of the dies working loose and rotating during the striking process”.

The first-year 2015 £2 Britannia is already one of the most-scarce circulating £2 coins ever issued with just 650,000 coins passing through banks and cash centres.

We have analysed 5,000 circulation coins and our results suggest that the Inverted Effigy may have affected as few as 1 in 200 of the coins struck – in other words around just 3,250 coins.

Dual Dated £1

Following reports by Change Checker and in the national press of dual dated 12 sided £1 coins, The Royal Mint has officially confirmed the error caused by a die mix up.

nations of the crown mule 2 amends - Why the latest Royal Mint “error” is the hardest to find yet. Plus what it might be worth…
The error is so small, it cannot be seen with the naked eye.

However, this is one of the hardest errors ever to spot because it’s incredibly difficult to see the micro-engraved date on the reverse.

It’s worth checking any 2016 coins just inside the rim of the design-side of the coin, where you will see some tiny writing. You’ll almost certainly need a Microscope or Phonescope to properly see the writing, which should reveal the date. You’re looking for a 2016 obverse-dated coin with 2017 micro-engraving on the reverse.

The Royal Mint has given no indication of how many Dual-dated £1 Coins ever went into circulation – and it’s quite likely they do not even know. This makes it difficult to put a value on the coin, but we understand that at least one example was sold for £2,500 to a buyer in Spain in 2017, which probably marks the likely ceiling for value.


2007 Abolition of Slavery £2

There is a misconception that there were two types of the Abolition of Slavery £2 coin struck for circulation. It is true that two versions of the coins exist– one has a textured finish whereas the other has a smooth finish and features the artist, David Gentleman’s initials (circled).

2007 Myths blog
The Abolition of Slavery £2 Coins

The key difference is that only the textured version was struck for circulation, and if you find one of the smoother types in your change, you have actually found a coin which has been taken out of a presentation pack. This makes it considerably rarer than the circulating version, so it is worth keeping rather than spending!

The 2005 Gun Powder Plot £2 spelling mistake

The 2005 Gunpowder Plot £2 commemorates the 400th anniversary of Guy Fawkes’ failed assassination attempt on King James I, but the coin is more familiar to collectors for having a spelling mistake in the edge inscription.

The 2005 Gunpowder Plot £2 Coin Spelling mistake

The timeless quote “Remember, remember the fifth of November” has been found with various combinations of Pemember, Pemembep, Novemebep and so on. The common factor here is the ‘R’ which appears as a ‘P’.

Sadly for collectors this is apparently not a striking error. The explanation from The Royal Mint is that the down-stroke of the R coincides with the milling around the edge, and as the coin has worn over time, the letter has become less defined.

This categorical statement from the Mint means that any mark-up in price for a supposed ‘error’ is completely unjustified, and although it makes the coin more interesting, it is not the mistake which it is often perceived to be.

The Battle of Britain 50p with no denomination

The Brilliant Uncirculated 50p was issued early in 2015 and was quickly dubbed an error coin. The coins, which were sold in presentation packs, had been struck without the denomination in either numbers or writing anywhere on the coin.

After the controversy surrounding the coin erupted, The Royal Mint confirmed that the 50p intended for circulation later on in the year would have the ’50 PENCE’ denomination.

The Battle of Britain 50p with three different obverses

Although this Battle of Britain 50p fails to feature a denomination on the Brilliant Uncirculated version and despite the fact that each obverse is different, The Royal Mint claim this was intentional and therefore is not an error.

Upside down edge lettering

Depending on the denomination, some coins will have edge lettering to help against counterfeiting. What you may not know though, is the edge lettering is applied before the coin has even been struck which is why some coins can end up with the edge lettering upside down.

A £2 coin with upside down edge lettering

It’s the little details like these that make collecting so interesting – and hopefully we’ve shed a bit more light on some of the most popular coin mis-strikes and myths in UK coinage. The minting process is never completely exempt from human error, so remember to always check your change carefully.  Mistakes happen, and when it comes to coins, these mistakes can often be worth a lot money to sharp-eyed collectors.


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It’s regarded by many as the Holy Grail of change collecting, and back in 2008, the undated 20p saga encouraged an entire country to start carefully checking their coins. In fact plenty of collectors are still doing just that in the hope of finding one.

Online sellers have set prices sky high, with one seller asking for an astonishing £10m for the the coin! However, although these chancers are unlikely to see their coin actually selling for that price, some people have been willing to pay in the thousands for the chance to own one of these rare coins.

The story of the coin

If you’re not familiar with the story of the undated 20p, this is it:

In 2008, the reverse of each denomination from 1p to £1 was redesigned by Matthew Dent to feature a different part of the Royal Arms Shield. The 20p had previously included the date on the reverse, but with the entire face of the coin now devoted to the new design, the Royal Mint produced a new die with the date on the obverse (Queen’s head) side.

However, when the new Royal Shield 20p coins were struck for circulation, the old die was accidentally used, meaning a batch was issued with no date on either side of the coin.

Coins with mismatched sides like these are known in the collecting world as ‘mules’ – the name deriving from the hybrid offspring of a horse and a donkey. Mule coins are always highly coveted, but they rarely receive the kind of mainstream media attention afforded to the undated 20p.


The undated 20p

The undated 20p was the first coin issued for circulation in over 300 years without a date on either side


The first for 300 years

The undated 20p became the first coin in over 300 years to enter circulation without a date, and when the story broke in the press, it caused a frenzy not just in the collecting world but amongst the general public who realised they stood just as good a chance as anyone of pulling one out of their change.

Estimates have varied over the years but The Royal Mint confirmed in a statement that no more than 250,000 coins made it into circulation.


Media speculation fuelled wild estimates about the value of an undated 20p

Various stories in the media helped to fuel wild estimates of the value of an undated 20p


Stories from numerous media outlets fuelled rumours about the coin’s value. Experts suggest that the faulty 20ps could be worth £50 each, however sellers on eBay listed the coins for thousands, with one lucky seller fetching a colossal £7,100 (35,500 times face value). 

Of course, a coin with such a high mintage could never really be worth that sort of figure, and in recent years the average selling price for an undated 20p has levelled off. Nowadays they normally sell for around the £50 mark which I’m sure you’ll agree is still not a bad return for a 20p coin!

In terms of rarity, you are approximately twice as likely to find an undated 20p as you are the famous Kew Gardens 50p. However, ordinarily an undated 20p will sell for more. But why?

The reason quite simply is that everyone loves a good story.

The fact that the coin only exists by way of a freak accident really adds to its appeal, and makes it a collector’s item in every sense of the term. So remember to have a good look at your 20p next time you’ve got one in your hand. A flip of your coin could be worth a lot more than you thought.



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– Find and identify the coins in their pocket
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I receive queries on a daily basis from collectors who are keen to know about the origin of their coins and their design. This is in essence what Change Checker is all about – finding a distinctive coin in your loose change and having the intrigue to find out more about its design and history.

But the most common question is how much is my coin worth? Coins are no different to any other kind of collectible in many ways; there are certain criteria which you should always look out for, and which can help you to determine how collectible or valuable your coin is. Often It’s a very difficult question to answer, but I have put together my top four points which are the most important factors to consider.

1. Condition

The stark difference in quality between a circulated and uncirculated £1 coin.

The stark difference in quality between a circulated and uncirculated £1 coin.

Circulating coins as you would expect are subject to a lot more wear and tear than the coins you find in presentation packs. This is detrimental to the coin’s value because the design begins to lose its shape and definition. Of course, some older coins can maintain desirability because of their history, but on a like-for-like basis, a coin with clear definition in the design will certainly be more valuable than the one which has worn down over time. The sooner you can take your coin out of circulation and add it to your collection, the better.

Whilst collectors do favour coins which are in a good condition, I should also emphasise the importance of not cleaning your coin to try and improve its appearance. This can irreversibly damage the coin and in fact lower its value. General dirt can be removed with a damp, non-abrasive cloth but you should always try and avoid using any chemical-based product.

2. Scarcity

Kew Gardens

The Kew Gardens 50p hit the headlines in February 2014 for being the rarest circulating coin

Scarcity is possibly the most important factor to consider when trying to determine a coin’s value. Generally speaking, a scarce coin will sell for considerably more than a common one. The Kew Gardens 50p for example is the scarcest of all UK circulating coins; there are just 210,000 in circulation out of approximately 1 billion fifty pence pieces. In February 2014 the British press broke this story and speculation over the coin’s value escalated the price to the point where some were being offered for hundreds of pounds.

Coins are no different to other kinds of commodities in that respect – price is determined by the basic laws of supply and demand. Higher demand is created by a low mintage, which drives the market price of the coin upwards. In the case of the Kew Gardens 50p, this price was artificially high given that the coin is one which you can find in your normal change. But since then the coin has achieved an almost legendary status, meaning finding one today is extremely difficult – most have been squirreled away into private collections.

3. A story

Approximately 100,000 undated 20ps entered circulation in November 2008. It is a rare example of a ‘mule’ coin.

This can often tie-in with rarity, as the coins with a good story behind them tend to be the ones which are difficult to get your hands on! The “undated 20p” is a recent example of a such a coin. It is known as a ‘mule’ – a coin with a mismatched obverse and reverse (heads and tails). The name derives from a mule being the hybrid offspring of a horse and donkey.

In 2008 when the reverse of the 20p coin changed to the new Royal Shield design, approximately 100,000 coins were accidentally struck with the previous obverse die and therefore there was no date on the coin. In a similar way to the Kew Gardens story, some of the prices being quoted as a result of media coverage were extraordinary. Mules are highly sought after by collectors, and an undated 20p will certainly be worth more than its face value in years to come.

The undated 20p is not the first coin to capture the imagination of collectors. In 1933, there were already enough pennies in circulation so only around six or seven were produced with that year date. With no precise record of the number struck, it seemed perfectly feasible for one to turn up in everyday use, prompting an entire generation to begin checking their change. One of these elusive 1933 pennies would be worth around £50,000 in today’s market.

ST-Change-Checker-Spot-the-Difference-Olympics-Aquatics-50p-Coin (2)

The original Aquatics Olympic 50p design was withdrawn quickly, and not many made it into circulation

Do you recognise these Olympic 50p designs? If you’ve got the one on the left, it could be worth a great deal more than 50p. The Royal Mint initially struck the Aquatics Olympic 50p with the waves flowing over the swimmer’s face before changing the design to make the face more visible. None have recorded an officially catalogued selling price to date, but this ‘error’ coin is exactly the sort of thing which collectors look for, and a three-figure sum for this particular 50p is not unlikely.

4. Striking

ST-Change-Checker-Proof-v BU 50p-CoinThe coins we find in our everyday change are finished in a completely different way to the coins in specialist packs and sets.

As a collector you may already be familiar with the various striking methods, but the two main types of finish are as follows:


  • Uncirculated

Uncirculated coins are exactly what they say they are – coins which have never entered circulation. They are struck in the same way and from the same metal as circulating coins. Ordinary uncirculated coins can have scuffs and minor imperfections whereas brilliant uncirculated ‘specimen’ coins are issued specially for collectors and have a higher value attached as they have been handled and produced with more care.

  •  Proof

Proof coins are produced with a much higher standard of finish than the coins in circulation as they are collected purely for their numismatic value. Proof coins will often have an edition limit and specific theme or appearance which collectors look for. They are struck using special dies which are used fewer times and polished between each strike. They have a far more detailed appearance and are produced in much smaller quantities, making them inherently more valuable.


The truth is that most coins are worth only their face value. They have been produced extensively for centuries, and far outweigh the number of coin collectors. Therefore the chances that you’ve got something that nobody else has seen before are very slim indeed, but that chance does still exist…

The quick answer to any Change Checker who is curious about the value of their coin, is that if it is legal tender, it will always be worth at least its face value.

Beyond that, they key question is how desirable is it to a collector?

A coin is worth as much as someone is willing to pay for it, and there is no black and white guide for this. Just remember, you should never underestimate the importance of checking your change. It’s often the little details which make the big difference to a coin’s value.

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