Rare undated 20p coins - beware of standard coins!

In the news yesterday (29 Jun 09), it was announced that there are some rare "mule" 20p coins in circulation. Suddenly eBay is full of people selling their 20p coins. Whether innocently or not, many of these listings are for normal 20p coins. There are several listings where it looks likely the winner bidder will be very disappointed to have paid an inflated sum for a normal 20p coin.Note that even a rare coin is unlikely to be worth more than 50 to a collector, so the winner of item 180370987091 who bid 5,800 may have got carried away!What makes a 20p rare? Look for the new-style back, with part of the shield design. These coins should have the date on the front (head). A rare coin does not. You can have some confidence in the coin you're bidding for if you can see both sides of the coin, and neither side has a date on it.