AN INCREDIBLY rare coin from the year of the USA's Declaration of Independence has been discovered – at the bottom of a toffee tin.

Known as a Continental Dollar, the coin, measuring 38mm across and made of pewter, was minted in 1776 in the United States after being designed by Benjamin Franklin.

It had a limited production run with only around 6,000 believed to have been made and it’s thought that as few as 100 remain.

An estimate of £20,000 - £30,000 has been put on the coin though it could potentially reach a six-figure sum.

Auctioneer Joseph Trinder from Wotton Auction Rooms in Wotton-under-Edge said: “This coin represents a discovery that is in the top five of my career to date, and the sort of thing every auctioneer up and down the country hopes they’ll find.

“We discovered it in a large toffee tin a private vendor brought to us, full of all manner of interesting sorts of knick-knacks - other coins, little bits of jewellery, carved stone and fossils.

“We had a jolly good look through and made sure we got to the bottom of everything inside.

''There were some really interesting pieces like gold coins and some other valuable items, but, languishing at the bottom of this tin of treasures we found this amazing Continental Dollar coin.”

Because of the coin’s rarity and potential value, and the fact that many fakes exist, it was taken back to America for its authenticity to be verified by the Numismatic Guaranty Company, experts in grading coins.

“It was examined by a committee of specialists and X-rayed and put through other scientific tests, and we were delighted to receive a notification a few days ago to tell us that it is genuine,” added Mr Trinder.

“To think this is a coin that dates back to the year of independence, and to have it found in the UK is unique. We haven't been able to find a record of another example found here in Blighty,” said Mr Trinder.

The Continental Dollar will be the star of a specialist sale at Wotton Auction Rooms on Thursday, October.