Tell us about the character of Edward Bellingham – what do you think motivated him to pursue his ‘arcane research’ and his interest in the occult?

Bellingham is obviously a child of money and privilege, but he didn’t fit into the model of what a man of the time should be, and so consequently I think rather than trying to conform he went further the other way and go, I’m going to ‘un-conform’ – because society doesn’t recognise somebody like me, so I’m not going to recognise this society – I’m going to look elsewhere.

Bellingham gives the impression that of all the characters he’s the most attractive because he’s a bit of a flirt – but he also just has a sense of freedom about him that the other characters don’t have. Do you think that’s fair comment?

That’s what Mark always wanted, he said: have fun with this, he is naughty, he is flirty, he’s sexually totally ambiguous. Enjoy all of that, it’s not pure naturalism, it’s ever so slightly heightened. That’s the joy of this, and that’s what people want.

And there’s a lovely thing about him as a person: he’s travelled, he’s unlike Kit’s character, you know, he’s been around, he’s been to Egypt, he’s seen the Middle East, he speaks other languages he’s a Bohemian! And as a result a much freer person – much less English, if you like.

Where did you shoot Lot No. 249, and what was the highlight of the shoot?

We shot it in far North London [Hertfordshire] at a place called Rothamsted Manor, which was a Queen Anne period house, but had obviously had different functions over the years. It was one of the few period houses in and around London I’ve not filmed in and I loved it – it had an enormous amount of character and spirit, and the art department had converted these rooms that could otherwise have been quite mundane into an absolute forest of antiquity. It was just beautiful to step into the set and go, my God, this is accomplished film-making that people are doing here.

I think the highlight of the shoot was being slapped by Kit Harrington repeatedly, that was a lot of fun.

Are you a fan of Arthur Conan Doyle?

I’m a huge fan. My father read them to me when I was a child, I’ve read a lot of the stories myself and I’ve listened to a lot of them on audiobook.

And are you a fan of ghost stories yourself?

Absolutely. And I fundamentally believe ghosts exist even though I have never met one or seen one I believe they exist, and I consequently love ghost stories – especially when they’re done really cleverly. Mark has a way of not just delivering a great story but blending it with wonderful tropes that a lot of younger film makers probably won’t know, like Hammer House music scores. Mark knows everything about everything about everything! So he’ll go, I fancy a little bit of that one from a Basil Rathbone one that never got released and I’m going to throw in a little bit of this from a horror movie that only Quentin Tarantino has seen a print of – he’s so, so well versed, and that when you watch it makes for something unique and really interesting.

How would you persuade your next door neighbour to watch Lot No.249 at Christmas?

It’s the Christmas Conan Doyle chiller adapted by Mark Gatiss, I don’t think you need to do very much else – it sells itself! But if I had to summarize it I’d say it’s the story of three students in an Oxford college, one of whom is trying to bring a Mummy to life.

Mark Gatiss said you don’t physically resemble Bellingham but you have an “incredible combination of power and naughtiness” – like an evil cherub.

I’ll take that.

Mark Gatiss’ adaptation of the Arthur Conan Doyle short story comes to BBC Two this Christmas, starring Kit Harington and Freddie Fox.

1. Old College, Oxford plays host to three very different young academics: Abercrombie Smith (Kit Harington), a model of Victorian manhood, clean of limb and sound of mind; Monkhouse Lee (Colin Ryan), a delicate and unworldly student from Siam; and the strange and exotic Edward Bellingham (Freddie Fox), whose arcane research into Ancient Egypt is the talk of the campus. Could Bellingham’s unnatural experiments bring the breath of life to the horrifying bag of bones tagged Lot No.249?

An end-of-Empire chiller, Lot No. 249 stars Kit Harington, Freddie Fox, Colin Ryan, John Heffernan, James Swanton, Jonathan Rigby and Andrew Horton.

Watch A Ghost Story for Christmas: Lot No.249 on BBC Two and BBC iPlayer from 24 December at 10pm