*Warning – Doctor Who finale spoilers materialising: don’t read on if you haven’t seen finale The Doctor Falls*

Still gawping at the appearance of the First Doctor in the finale of this week’s Doctor Who? Well, the cameo was more magical than you might have thought: in case you didn’t realise, the show’s original Time Lord was played in his latest incarnation by David Bradley, the man who portrayed Argus Filch in the Harry Potter series.

Despite being a squib, the Hogwarts caretaker apparated onto the Arctic closing cliffhanger, trading Mrs Norris and his trademark scowl for the teacosy hat and white scarf that actor William Hartnell originally made famous in the 1960s.

David Bradley as William Hartnell/The First Doctor (left) and Filch (right)

However, if you’re more of a Game of Thrones fan than Harry Potter, you’ll recognise Bradley as Walder Frey, the ill-tempered Lord of the Crossing hated by pretty much all in the seven kingdoms, including many of his numerous children. He’s the one at the centre of arguably the show’s most shocking moment, one we shan’t delve into in case we give away a spoiler – absolutely nothing to do with us getting too emotional.

ANYWAY, Bradley’s had plenty of other screens roles, with his lengthy credits list including Hot Fuzz, Captain America: The First Avenger, Beowulf and Netflix’s Medici: Masters of Florence.

And yes hardy Whovians, he's also materialised in the Whoniverse before: during Matt Smith’s time as The Doctor, he played creepy black market trader Solomon in 2012's Dinosaurs on a Spaceship.

However, Bradley’s most prominent role was as the First Doctor, and the man who played him, in 2013’s An Adventure in Space and Time, the drama about the birth of Doctor Who.

So he was the perfect choice to play the First Doctor in the upcoming Christmas special, which – if the leading fan theory is correct – will see him team-up with Capaldi's Twelfth Doctor to set up events that occurred in 50th anniversary show The Day of the Doctor.

Doctor Who will return this Christmas