We were rather perplexed to see David Bradley aka Argus Filch from Harry Potter doing his thing in front of the Tardis this morning. Last time we saw him he was thrilling us in Broadchurch, and next time we see him he will indeed be playing a Time Lord, but it won't be the one who regenerates from Matt Smith.

The veteran star of stage and screen is actually filming a biopic about the history of the series, and is taking on the role of William Hartnell, who played the very First Doctor. Sherlock scribe Mark Gatiss has penned An Adventure in Space and Time, and is rather excited to have Bradley on board. "David Bradley brings every ounce of his talent, humour and presence to the role of William Hartnell," said Gatiss. "It's a wonderfully touching and subtle performance and I'm immensely proud of both him and the film."

Meanwhile there's still no word on who'll play the Time Lord in future, and showrunner Steven Moffat has said that he's finding the casting process a bit terrifying this time around. "If you're a Doctor Who fan, as I have been all my life, you've been doing fantasy casting for this part for as long as you can remember," he told Entertainment Weekly. "But when you're suddenly faced with the reality that you are going to sit there and you are going to make that decision it does feel absolutely chilling. There's a very big range of people who could play it and different ways you could go with it. We must get this right. One false move and the show's over."

Christmas is D-Day for Moffat and co so. They'll have to have the new Doctor ready to regenerate at the end of the Christmas Special y'see. "It'll be the traditional regeneration," he explained. "You know, the eleventh will fall and the twelfth shall rise. And you'll see that in the closing moments of the show. I mean, you sometimes sit and think, 'Are there better ways of doing it? Is there a different way of doing it?' But quite honestly what could be better than that? It's just too exciting."

And we can expect a full series with Doctor #13 at the helm of the Tardis in Summer 2014 too. Better get to work so lads, time stops for no man after all, though maybe they could stall it for a Time Lord, eh?