A COIN expert says he is “100 per cent sure” that the Roman coin found by two York metal detector enthusiasts in a field near Stamford Bridge is genuine.

Jim Brown, of Dix Noonan Webb, specialist auctioneers and valuers of coins, travelled to York from London yesterday to examine the silver coin.

The coin’s finders, Colin Popplewell and Mark Hildreth, say it is one of only two found in the world which feature Proculus, the “usurper” Roman Emperor of 280AD.

Mr Brown said the coin would be auctioned next spring and, while it was impossible to say how much it would fetch, £50,000 would be a conservative estimate.

Rebecca Griffiths, finds liaison officer at the Yorkshire Museum, said yesterday she had seen the coin but had not recorded it, as the metal detectorists had claimed, because she had concerns it might actually be a fake from the Renaissance period.

But Mr Brown, who said he had been involved with coins for almost 40 years, said it was definitely not a Renaissance fake.

“I am absolutely sure it’s Roman – 100 per cent,” he said, before taking the coin to London for safekeeping.