old roman name for the UK as being Cassiter Isles

From Brewer's Phrase and Fable (nod to Bill):

Cassiterides
The tin islands, generally supposed to be the Scilly Islands and Cornwall, but probably the isles in Vigo Bay are meant. It is said that the Veneti procured tin from Cornwall, and carried it to the Isles of Vigo Bay, but kept as a profound secret the place from which they obtained it. The Phœnicians were the chief customers of the Veneti.
http://www.bartleby.com/81/3126.html

Lots of links here on the Cassiterides and cassiterite:
http://webster.directhit.com/webster/search.aspx?qry=cassiterides

The upshot is that the Cassiterides were either Cornwall + the Scilly Isles (about as far SW as you can get in the UK) or a group of Mediterranean islands. Oh, and it was the Phoenicians "when Rome was still a tiny village on the Palatine Hill", who got their first. Or the Veneti (whoever they are) if you go by Brewer. Not the Romans, anyway, so not surprising if there are no Latin roots to the cassiteri- words.