Mark Gatiss has revealed the upcoming Christmas special of Sherlock is the first time he has actually written an episode with Steven Moffat.

The pair have been collaborating as creators of the TV adaptation of Sherlock since it launched in 2010, but haven’t actually sat down and penned a script together until now.

Mark, who also plays Sherlock’s brother Mycroft in the BBC series, told the Radio Times: “Over the years we’ve always been across each other’s Sherlock scripts because we want it to be holistic. But the upcoming episode is the first time we’ve actually written together.

“It’s been a real joy. I think it will carry on for the next series.”

Mark Gatiss Sherlock
Mark Gatiss as Mycroft in Sherlock (BBC)

The hit series, based on Arthur Conan Doyle’s novels and starring Benedict Cumberbatch and Martin Freeman, will return later in the year, and Mark explained how he had first fallen in love with the characters.

He said: “My mum got me The Adventures Of Sherlock Holmes when I had German measles, aged 10. I loved the flavour of Arthur Conan Doyle’s stories. He was a master storyteller and you get a brilliant snapshot of Victorian Britain.

“Sherlock happened because Steven Moffat and I were in the same place, singing from the same hymn sheets. The idea of making Sherlock modern again was one of these light bulb moments. We just looked at each other and went, ‘Someone should do that’.”