I've just acquired a rather nice, nearly EF, Briot second milled-issue sixpence on eBay (from a reputable seller) and am currently awaiting its arrival. It is slabbed by PGCS (AU55) so I should have reasonable grounds to believe it's not a copy. In my view, the obverse scratches do detract from the AU classification somewhat, but despite this it does look "right". However, I now notice that the reverse legend is CHISTO AUSPICE REGNO and not "CHRISTO" and there is no such variation listed by Spink or North. Could this be an unknown variety or maybe a contemporary fake? Obviously PGCS did not think the latter and for a contemporary fake I believe the die detail is too authentic. Before purchasing I, of course, checked the slab reference number which is genuine for a Briot sixpence of this description. My thoughts on this is that maybe it was a die mistake that was only noticed after coin(s) had been struck then presumably would have been withdrawn. Any expert views on this would be welcome.