Can you give an overview of Lot No. 249?

On the surface it’s a ripping old yarn about an Egyptian mummy terrorising an Oxford campus! Freddie Fox releases a murderous zombie and my character smells a rat and tries to stop him. But maybe once you release something like that… it can’t be put back in its box! It’s a really fun caper penned originally by Conan Doyle and made into a wonderfully scary and frightful Christmas ghost story by the marvellous Mark Gatiss.

Tell us about your character – Abercrombie Smith?

He plays with a straight bat! Very proper. Doesn’t want anything disturbing his world order. Doesn’t trust anything that’s not out of the text books of the time… he’ll stick to his phrenology and be done with it, thank you very much!

What was it like working with Mark Gatiss and your fellow cast members – Freddie Fox et al?

A dream. I have loved Gatiss and his work for a long time and I adore his series of Christmas ghost stories. Freddie is a great, kind, generous and brilliant actor. It was rapid and fun and that was what Mark promised me. Let’s get in, shoot something fun and sit around at Christmas with mince pies and watch it. What a joy.

Did you know much of Conan Doyle’s work (outside of Sherlock) before you took on this role? What did you take away from the experience?

No. Outside of Sherlock I didn’t. This has all of the elements that we love in Sherlock though… the intrigue, the fantastical. I guess I take on the ‘Sherlock-like’ role in this piece…. but Smith is far too much of a box thinker to succeed in the ways Sherlock does.

I really enjoyed the period and how unashamedly ‘Victorian’ we were encouraged to play the parts. I knew that there was great room for play in the role with Mark directing and that was wonderfully liberating.

Mark Gatiss says you really embodied the Victorian gentleman. Did the costumes and location help you bring the character to life?

Mark clearly saw that I’m a closet Victorian man trapped in a millennial body. I loved these costumes, I loved the moustache…I’d definitely do something of this period again.

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

I mean what’s not to love. Egyptian killer mummy, Mark Gatiss directing and writing, Freddie Fox being evil, period costumes and silly moustaches. It’s nice and short and fun and will only give you minor nightmares!

Were you impressed by James’ transformation into the Mummy?

He was genuinely scary. When he ran it was one of the more disturbing things I witnessed this year. We called him ‘mummy’ on set, it’s quite a Freudian piece really.

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