Islamic British coins. Now there's a phrase we don't see often used. But apparently they did exist during the 8th century (Dark Ages). They were minted by Offa of Mercia, and were a copy of an Abbasid dinar struck in 774 by Caliph Al-Mansur (ref: http://www.britishmuseum.org/explore/highlights/highlight_objects/cm/g/gold_imitation_dinar_of_offa.aspx )
It's fascinating in itself, but it's even more fascinating to have discovered that fact in a book on national identity by Billy Bragg. I don't know what I expected, but it wasn't that. And it's going to lead to an interesting collection of tags for one entry in the blog...