Robert Ferguson visited London from his home in Oslo earlier this week and I interviewed him at his publisher’s offices for the Blackwells podcast which will go out tomorrow. Robert has just published a major new history of the Viking age called The Hammer and the Cross, in which he says he wants to “restore the violence of the Viking age”, but also to explain the context in which that violence took place – namely the enforced Christianization of the northern peoples by Charlemagne. Is it, Robert wonders in the Blackwells interview, out of place to compare the dynamic driving those Viking raids to modern acts of terrorism? I also made this short film with him in which I confess the questions were a bit more straightforward: so did the Vikings wear horned helmets? Click below to find out [3:37].