It’s fair to say that Doctor Who fans have plenty of big questions about the upcoming Christmas special Twice Upon a Time.

Questions like: ‘How will Peter Capaldi’s Twelfth Doctor regenerate? What will new Doctor Jodie Whittaker be like in action? How will the return of Pearl Mackie’s companion Bill be explained? And why is the First Doctor back anyway?’

But equally intriguing is what you might call a second-tier mystery: who is the character played by longtime series writer (and sometimes actor) Mark Gatiss, a First World War soldier described only as “The Captain” who appears to be trapped in a single moment of time in the special’s previously-released trailer.

So far, nothing else has been revealed about his identity, leading some fans to question whether he could be a younger version of classic series ally the Brigadier (Nicholas Courtenay) or even some sort of Time Lord himself (the definite article name is certainly bang on).

But now, a few Whovians think they may have cracked who Gatiss is supposed to be portraying – and if they’re right, it’s a character with incredibly specific ties to the origins of Doctor Who.

You see, a little while ago some historically-minded fans noted one of Gatiss’ lines in the trailer – “These Police Boxes, they’re ever so good, aren’t they?” – and it set their minds a-whirring back to another First World War soldier with an eye for square, blue constructions.

His name was Gilbert MacKenzie-Trench, a surveyor and architect working for the Metropolitan police, known for designing police stations, residential buildings and other constructions throughout the 20th century, and who fought in the First World War in his late 20s and early 30s. As you can see in this colourised picture (restored by Petra Caroline), he even looked a little like Gatiss does in the official images (and footage) released from Twice Upon a Time thus far. Note the similar left parting in particular…

‘But what does any of that have to do with Doctor Who?’ you may rightfully be asking. Well, among all his achievements MacKenzie-Trench is probably best known for one of his smaller designs – the blue Police Box, adopted from 1929 (other less official versions had existed before this) and spreading across the UK over the following decades.

And of course, the blue Police Box that he designed later became famous worldwide when it was adopted as the outer appearance of the Doctor’s Tardis, with the character’s time-travel capsule becoming stuck in that camouflage form after visiting the 1960s.

Just think about it. The historical MacKenzie-Trench becoming inspired to create the real police boxes after encountering the Tardis would be a VERY Doctor Who idea (rather like Agatha Christie getting her ideas from the Tenth Doctor and Donna in The Unicorn and the Wasp), and yet another way for departing showrunner and episode writer Steven Moffat to pay tribute to Doctor Who’s history in his last hurrah.

And given that the little we’ve glimpsed of Gatiss’s character sees him expressing admiration for the police boxes of both Time Lords (notably, he seems most enamoured with the more 1960s version piloted by David Bradley’s First Doctor), it doesn’t seem too much of a stretch to imagine that Doctor Who is pilfering from real history to create a neat little circularity to the series’ origins.

Then again, it could be that we’re wrong and we’ve spent a whole morning researching the history of police boxes in the UK for no reason. Either way, we’re pretty happy with how we’ve spent our time.