Why this “error” is the hardest to find yet. Plus what it might be worth…

In 2017, following reports by Change Checker and in the national press that a die mix up at The Royal Mint resulted in a number of 12 sided £1 coins being struck with dual-dates, The Royal Mint officially confirmed the error.

However, this is one of the hardest errors to spot. That’s because even with 20/20 eyesight you will struggle to see the incorrect date on the coin’s reverse because it’s micro-engraved as part of the coin’s ultra-secure finish.

The error is so small, it cannot be seen with the naked eye.

What do I need to look for?

Firstly, although both 2016 and 2017 obverse-dated £1 coins entered circulation in April 2017, the die-error mix up appears to have only occurred on a limited number of coins with a 2016 date on the Queen’s head side.

So it’s worth checking any 2016 coins. You’ll need to look 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 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.

What if I can’t read the micro-engraving?

With over 1.75 billion 12-sided £1 coins being struck between 2016 and 2022, not all coins are finished perfectly. Unfortunately, a poorly struck example where you cannot read the micro-engraving is not of great interest to collectors.

The reverse date engraving can be extremely hard to see with the naked eye

What about other £1 mis-strikes and errors?

We believe this is the only known £1 error. Due to the huge number of coins that have entered circulation, there are a number of interesting mis-strikes, which, although numismatically interesting, have relatively limited collectability or value.

More worryingly, there are a number of altered £1 coins for sale, claiming to have misaligned heads or similar unusual errors. However, both these are likely to have transgressed the Coinage Act by tampering with the coin and are clear minting impossibilities. STEER WELL CLEAR is our advice. Similarly, beware of photographs that purport to show a genuine Dual-dated £1 coin – you need to be confident you’re not simply looking at two different coins.

So how much is a Dual-dated £1 Coin worth?

This remains the most difficult question to answer, but let’s take a look at the available information.

  1. How many were struck?

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. We’ve not seen any examples amongst our stock. Equally, 1,500,000,000 2016 £1 coins were struck and rates of 1,800 coins per minute were achieved at the height of production.

The key number seems to be how many coins The Royal Mint strike before they replace a die. Given the nature of the “error” it seems likely that it was only corrected when the die was replaced. Understandably, the number of coins The Royal Mint strikes with each blank is not something the Mint chooses to share for commercial reasons.

  1. What are the comparables?

The key to any valuation is what comparable coins sell for. The most obvious comparable is the 2008 undated 20p, which was caused by a similar die mix up. That sells online for up to £64.

Other interesting UK errors include “Silver” 2p coins, which have sold in recent years for as much as £1,400, but these are considerably rarer, relying on a few old 10p blanks being left over when a blank barrel has been filled with new 2p blanks. Another 2 pence error, when some 2p pieces were struck using the old decimalisation dies with the word “NEW” in front of “PENCE”, have sold for around £60.

The 2015 Rare ‘Silver’ 2p
  1. So what is a Dual-dated £1 Coin worth?

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.

Probably more Dual-dated £1 coins have been struck than the 2p coins. However, the error is particularly difficult to spot due to the size of the micro-engraving. Bearing all that in mind, our best value estimate for a Dual-dated £1 Coin in excellent condition is currently £300 – £500.

Finding the coin in your change

We’ve heard from two Change Checkers lucky enough to find a dual dated error, one in October 2018 and one in April 2019.

I’m sure that the challenge of finding a dual dated £1 coin has sparked many Change Checker’s interest in collecting coins and I’m sure will encourage more collectors out there to look more closely at their £1 coins.

Dual dated £1 error coin found by a lucky Change Checker

If you’ve come across an interesting coin in your change, be sure to get in touch with us. We’d love to hear about the rare coins you’ve found!


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How does it feel to design the UK’s newest circulation coin? I caught up with Aaron West to find out.

Aaron West is part of the design team for The Royal Mint and is responsible for designing the latest coin released into circulation, the Sir Isaac Newton 50p.

Aaron West, a designer for The Royal Mint, signing the new Sir Isaac Newton 50p coin pack

This is the second circulation coin designed by Aaron, the first being the very popular Great Fire of London £2.

The two UK circulation coins Aaron has designed – The Sir Isaac Newton 50p and The Great Fire of London £2

I wanted to find out what makes a coin designer tick and Aaron kindly answered some of my questions:

How long have you been designing coins for The Royal Mint and how many have you designed to date?

I have been designing coins for over four years now. I have designed many coins but have been fortunate to win two design competitions.

How did you become a coin designer for The Royal Mint?

I joined The Royal Mint in June 2011. I applied for a maternity cover position and then was given a permanent position. I have been working as a designer for over seven years.

Which coins have you designed for The Royal Mint?

I have official coins designs for a £2 coin, The Great Fire of London and for a 50 pence piece, Sir Isaac Newton. 

Aaron sketching his initial Sir Isaac Newton 50p design ideas. (Image: The Royal Mint)

Can you tell me briefly the process involved when designing a coin?

There is no specific process involved when designing a coin. It depends on the subject. For example, The Great Fire of London, I broke it down to three elements. Firstly I concentrated on the bottom of the design (the river and boats) then I moved onto the middle part of the design (buildings / skyline). The third / top part of the design (the smoke) was the most difficult part. I try to keep all of my designs simple because a lot of detail will not be clear on a small diameter. 

Approximately how long does it take to design one coin?

Again, it all depends on the subject. I try to spend a few days on research before I start my design concepts. If the subject is complex then I’ll spend more time on research. It takes me approximately an hour for each design (rough sketch).

These sketches show the stages of the design process for the Great Fire of London £2 (Image: The Royal Mint)

What is the most challenging aspect when designing a coin?

The most challenging aspect when designing a coin is trying to fit everything in a small area. Coins are very small so to make a design stand out is very challenging.

How do you feel when you receive a coin that you’ve designed in your change?

Unfortunately, I have yet to find any of my designs in my pocket change but I am still looking. Some of my friends and family have found them and messaged me some pictures which was very thoughtful.

I am pleased that people are looking for them which makes me very proud. I am also very proud to a part of history. 

The Isaac Newton 50p coin has a very intricate design for a small area

Finally, other than one of your own (obviously!) what is your favourite coin design and why?

My favourite coin design would have to be the Jane Austen £2 coin. I like the portrait which is featured in the centre but I particularly like the inner silver edge. The inner silver edge is a picture frame which works very well. I also like the stripes which on the design, they stand out. 


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