I stand by further working for all these situations and farther is merely a linguistic variant of the same word. The BBC represents pretty much the gold standard of how this works, though we may possibly be getting into 'American' English vs 'English' English.

I maintain that the "distance vs. figurative" rule is not backed up by actual users of the language either now or historically. Like the preposition rule, it was dreamt up fairly recently in an artificial manner that does not reflect the actual usage of the English tongue.