The discovery of two coins separated by the cataclysm of the Black Death could change our understanding of Britain's medieval economy.
A 23-carat gold 'leopard' issued in 1344 was found in the Reepham area, near a gold noble minted in 1351-2.
Dr Helen Geake, archaeologist and Norfolk finds liaison officer, said it was the first time two such coins from the reign of Edward III had been found together.
Dr Geake said leopards were extremely valuable, and almost none had survived.
"When the leopards are minted it's the first time in 500 years we've had gold coins in this country," she said.
"Until then, if you wanted to buy something significant like a cow or a horse you would have to carry a great pack of silver pennies.
"But for some reason the leopards weren't popular, it seems they weren't worth what they said they were. It overvalued the gold against the silver."
The leopards were recalled and less than a year later the minting of nobles began - which were more widely adopted.
Separating the issue date of the two coins was the arrival of the bubonic plague - also called the Black Death - in 1348, which killed 30pc-40pc of England's population over the following few years.
Dr Geake said why this leopard was not recalled along with the others is a mystery.
She said: "Almost none survived because they were all pulled back in and reminted, and this is the first time that we know of that one has been found with another coin.
"It implies that this leopard is either in circulation or being held onto by someone who thinks it is worth it, which is weird behaviour."
"This is the first leopard that comes from a hoard, so it now suggests that it's possible some of these coins stayed in circulation.
"It means the picture is more complex than thought."
Mr Geake said the coins, which were found in 2019, would have been worth the equivalent of around £10,000 to their owner in the 14th century.
Their status as treasure is subject to a coroner's inquest, scheduled for June 23.
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