The Royal Mint in Lantrisant - the place where all the coins in Britain are made - have made a royal mistake, and we couldn't be happier about it. During a recent re-design of the twenty-pence piece, they decided to move the date from the back of the coin (tails) to the front (heads).  But while the back was changed successfully, it seems someone forgot to add the date to the front of the new coin and, as a result, an unknown number of 'dateless' twenty-pence pieces were released into circulation before the mistake was realised.

Now, to the average person that may not seem like a big deal.  But avid collectors are desperately trying to get their hands on these rare twenty-pence pieces, and are paying handsomely for them.  When news first emerged of these rare coins - known as 'mules' by collectors because of their mismatched sides (a reference to the mule being a mismatch of a horse and a donkey) - their value was estimated to be £50 each.  But as word spread and people hurriedly emptied out their pockets, desperate to find a 20p worth £50, their value has continued to soar.  Yesterday one coin was sold for £7,100 on eBay... that's 35,500 times its face value!  Others are asking as much as £20,000, although at the time of writing nobody has been crazy enough to pay that.

How do I know if I have a 'mule' 20p?

As I write this, a lot of people are glancing at the 'heads' side of their twenty-pence pieces, realising there's no date, and rushing to eBay to make their fortune.  Before you do this: turn the coin over.  All coins are missing a date on the 'heads' side, because the date traditionally goes on the back ? that's what makes this new design interesting.  In order to confirm whether you have a 'mule' coin, the design on the back of the coin must be the new design (see picture).  If the back of your coin has the new design (with no date) and the front of your coin has the Queen's head (with no date) then guard that coin with your life because it's worth a lot of money!

Beware of scams

As I have mentioned above, only a coin with a missing date on both sides is valuable.  A 20-pence that just has a missing date on the 'heads' side is still only worth 20-pence.  Keep this in mind should you visit websites such as eBay, as there are a lot of scammers preying on people's ignorance.  There are countless scam auctions where regular 20-pence pieces are being sold for £50 and marketed as '20p with NO DATE on Queen side'.  Don't fall victim to their trap.