But if the Romans had carted it away during their occupation of Britain, before there was an England, then I would not think that modern day England would necessarily have much claim for assuming ownership of it.
I agree with you. It all depends, I suppose as to where the Romans carted it. If it was carted to the Falkland Islands, the Brits might still be in luck. If it was carted to Gaul/France - forget it!
BTW: what's your thought regarding the 2001 Supreme Court decision that upheld the right of Spain to reclaim their shipwrecked vessels - even though they were shipwrecked on US territory? I must admit, that one surprised me.