This gold coin of Coenwulf, king of Mercia (796-821), is unique, and one of only eight gold British coins known from the period AD 700-1250. It is unusually well-preserved, and must have been lost very shortly after it was first issued. This is the earliest of the gold coins which we can be certain was intended for use as regular currency at home and abroad. Some of the others were certainly intended as presentation pieces, although it is not known whether the famous Offa dinar - minted by Coenwulf's predecessor - was intended for presentation or used as currency.Coenwulf was king of Mercia, East Anglia and Kent, making him ruler of most of England. We know from letters that Offa wanted to be seen as the equal of the Frankish ruler Charlemagne (769-814). Could this coin show that his successor Coenwulf felt the same? The coin refers to London as a vicus, or trading centre, and a gold coin of Charlemagne uses the same term to describe the major port of Dorestadt, at the mouth of the Rhine. Both Coenwulf and Charlemagne's coins give the ruler's name and title, and both rulers are shown as Roman emperors. The similarities suggest that Coenwulf wanted a gold coinage to rival Charlemagne's.