Rare 20p coins: Check online

The London Mint Office is offering £50 to anyone who finds a new 20-pence piece without a date on it.

The www.undated20p.com website will help you identify the coins, which should have had the year 2008 printed on the side with the Queen's head.

You are under no obligation to sell the coin should you find one, but if you do want to sell it back to the London Mint Office you'll have to register on the site first.

Only 10,000 registrations will be accepted so you'll have to move quickly if you want to sell yours.

It is not known exactly how many coins were mistakenly printed without a date - something that hasn't happened in 300 years - but estimates range between 50,000 and 200,000.

The London Mint Office is a coin collector not connected with Royal Mint.

Have you found one of the rare undated 20p coins? Have your say in the Web User forums.