SFX posted a snippet from an interview with Colin Morgan and Bradley James: link. LOL'd at this bit:
Have you shot in any memorable locations?
Bradley James: “On the hottest day of the year we shot in what was supposed to be a frozen landscape. It was roasting. We were sweating. And they were like, ‘Could you shiver more?’ ‘No. We can sweat more.’”
Colin Morgan: “We were getting snow blindness as well because it was essentially just a big reflector up in your face all day, but I think that stuff’s gonna look awesome.”