NLSS Child tells me there is a plan to reveal why the 12th Doctor has the same face as Caecillius and that man in Torchwood Children of Earth so we presumably will have to wait and see.

I'm interested to learn in the discussion above that in the textbooks only Quintus escapes Pompeii. I wonder if it was a deliberate fixit and the implication is supposed to be that the Doctor actually did change history.