0325 GMT October 24, 2020
The silver coin featuring the head of Alexander III of Scotland dates from 1280-6 and was discovered in Long Stratton, Norfolk in August 2019, according to BBC.
The penny was worn as either a pendant or brooch by someone who was religious, coin expert Dr. Adrian Marsden said.
He added that the coin "had traveled some way".
Marsden, a numismatist at Norfolk Historic Environment Service, said it "must have been eventually lost" in the county until it was rediscovered last year by a metal detectorist in a field, whose location is not being disclosed.
The historian said the item would have been worn as a religious symbol as the side with the cross was the one intended for display, rather than the head side of the coin.
"There is also settings for gems [which were no longer present] which represent the five wounds of Christ, so it is symbolic and adds to the religious dimension," he said.
Marsden believed the owner "would have been relatively well-off" as the penny was the equivalent of half a day's wage at the time.
"It would have been a bit of a luxury and the owner would have some social status," he said.
"The coin was probably equivalent to £20 in today's money."
The Norwich Castle Museum hopes to acquire the coin and add it to a collection of similar items.
It was declared treasure at an inquest at Norfolk Coroner's Court earlier this month.