Where are the tin miners in Cecilia Holland's "Pillar of the Sky" from?

Hi!

Cecilia Holland's Pillar of the Sky is set in the stone/bronze age; technology is traveling slowly through England at that time. I know I'm a good few thousand years out of period, but this is the most likely group I could find.

Early in the book the protagonist is kidnapped and enslaved by an exiled metallurgist who dreams of sailing back to his own lands and leaving the savages of England far behind.

I can not figure out from the book where the miner is supposed to come from. Is he Scandinavian, Phoenician, Greek, Etruscan? If the weather is fair, it is nine days sailing.

Is there anyone else familiar with the book who might have a clue or just a suggestion of where else I might ask? Or do you think the story just too improbable for that period?

Thanks in advance,

Somewhere Mediterranean - Phoenician or Greek seems likely - there were pre-Roman British tin ingots found on a shipwreck off the coast of Israel and other artifacts on the continent with British tin content.

https://en.wikipedia.org/wiki/Mining_in_Cornwall_and_Devon