Pensioner from Gilesgate, Durham, receives £50 for rare 20p coin

Nancy Laidman received the payout from The London Mint Office, a specialist coin collecting company which is paying £50 for 20p "mule" coins released following a manufacturing error at The Royal Mint.

The 71-year-old, from Goodyear Crescent, Gilesgate, Durham, plans to spend the money on her 10 grandchildren at Christmas.

She said: "I was very happy that I found the 20p. I looked through my collection of 20ps and found nothing and then surprisingly found one in the change in my purse."

The hunt for undated 20p coins began after The Royal Mint made a rare mistake, releasing a batch of undated new-design 20p coins into circulation.

The Mint does not know exactly how many undated coins were produced and released, but estimates range between 50,000 and 200,000.

This is the first undated British coin to enter circulation in more than 300 years - the last occasion being 1672.

The mule coins have the new tail side and old Queen's portrait side, bearing no date.

Public interest took off after The London Mint Office, which is unconnected to The Royal Mint, announced it would pay £50 for each undated 20p.

Within a few hours, the firm exceeded its initial limit of 10,000 applications from people pre-registering their interest, and has since extended the number of reservations to 25,000, to cope with the surge of interest.

Nick Hart, a coin expert at The London Mint Office, said: "The interest has been phenomenal."

The coins are bringing large returns on internet auction sites such as eBay, but Mr Hart warned not all coins listed are valuable.

"A number of people are listing the old design 20p which featured the date on the reverse," he said.

"These coins are only worth 20p but people are bidding more for them. People could be very disappointed if they buy them."

Anyone who finds an undated 20p can register their details with The London Mint Office before sending in the coin and claiming their reward.

For details, visit undated20p.com