The Royal Mint has admitted that some of the new £1 coins have been minted with a small mistake. This kind of production glitch can make coins highly desirable to collectors, so it's worth checking your change to see if you have a potentially valuable 'error coin'.
See also: Most collectible 50p designs revealed
See also: Number of vending machines that won't accept new £1 coin
See also: New 12-sided £1 coin to edge out old round pound
The issue came to light when a charity worker in Surrey noticed he had been given a coin that didn't feel quite right. The side with the Queen's head had the text out of alignment with the Queen, and several details on the reverse seemed unclear - including the crosshatching on the head of the thistle.
At the time he went to the papers and suggested that the coin could be an early fake, but the Mint confirmed it has not seen a single fake coin yet - so this is a production mistake. The Mint has so far struck 1.5 billion new £1 coins, and the speed and volume of production has meant that some imperfect coins have slipped through the net.
Is it worth a fortune?
Mistakes, which are known by collectors as error coins, can make otherwise dull coins highly valuable. There are some well-known examples - like the 20ps produced in 2008, which were accidentally printed without a date. One of these in perfect condition can be worth up to £200.
There are also a number of 2p produced in 1983, which should have had 'two pence' written on them, but accidentally had the old label of 'new pence' added. These can be worth up to £400.
Then there's the Britannia £2 coins, which accidentally printed the Queen's head almost upside down. One in 200 of the coins feature this error, and they can sell for up to £100.
The value of this particular error will depend on a number of factors - including how common the errors turn out to be, and the enthusiasm collectors show for the new £1 coin. Given that they are relatively small errors, they are unlikely to be worth hundreds of pounds, but if they prove rare enough, and collectors get behind the new £1, they could be worth a decent sum.
If you stumble across one of these coins, therefore, it's worth hanging onto it until we know how rare this error is. Just try not to be tempted to spend it in the interim.