English one was minted in London and is correct weight for a silver halfpenny. Its not billon as English halfpennies were good silver at the time, unless its a Flemming (A low quality copy from the low countries), and its been clipped, a halfpenny should weigh around 0.65 - 0.70 grams (11 grains). The French coins I know less about, possibly deniers or gros - they had inflation at the time.
It could be Edward I or II as well, as that effigy was not changed much and Edward was used on these coins up to the early 1380s in the reign of Richard II. The coin is too clipped to be an underweight or reduced size coin of post 1361, when the penny was reduced to 18 grains from 22.
I love coins. Especially silver, gold and anything really old.
Member of the Royal Numismatic Society of New Zealand and the Auckland Numismatic Society
