This coin came in from a detectorist signing himself as Lucas. He said it was unearthed in County Down, Northern Ireland and he wondered if I could provide a valuation.
The coin is 16mm in dimeter and is a halfpenny. Within the inner circle on the obverse is a head facing right and if the whole of the legend could be seen then it would read IOHANNES. On the reverse is a cross pattee with a fleur de lis and a pellet in each angle; the surrounding legend names the moneyer as ROGER.
At one time halfpennies of this type were thought to have been struck for John de Courcy. However, they are now believed to have been struck for Prince John. Therefore, halfpennies like this one were the first to be struck in Ireland for the Plantagenet dynasty. They are listed in Coins of Scotland, Ireland and the Islands as number 6203.
This is an extremely rare coin. A specimen was sold at auction back in 2013 for £5,800. However, that one was in better condition than this recent find. The reverse would grade Fine or slightly better but most areas are dark in colour. The obverse looks to be Fine and is also dark but the head of John is very clear. It has another minus point in that it has a very small edge chip.
Despite the overall condition not being outstanding, this coin is so rare that if I was cataloguing it for sale at auction my minimum pre-sale estimate would be £3,000.