'Element-hairy!': Benedict Cumberbatch and Martin Freeman begin filming Sherlock series 4 in Bristol

Co-writer Mark Gatiss has tweeted confirming that shooting is underway

Benedict Cumberbatch and Martin Freeman in the first look picture from next year's Sherlock special (BBC)

There may be almost a whole year to wait before Sherlock returns to our tellys, but fans can find some solace in the fact that shooting has already begun on the hit detective drama.

Benedict Cumberbatch and Martin Freeman are returning to their roles as Sherlock Holmes and John Watson for a fourth series of the show, based on Sir Arthur Conan Doyle’s classic.

Co-writer Mark Gatiss tweeted on Monday that he was en route to start filming, writing “On my way West. It begins…#Sherlock” on the social media site.

Shortly afterwards, Sherlock’s cast were spotted arriving at Bristol music venue Colston Hall and Gatiss posted a picture of a clapperboard, complete with a moustached face and caption reading “Element-hairy, my dear Watson!”.

The scenes currently being shot are for the show’s Christmas special, which will air in December before further episodes in 2016.

Producers hinted recently that viewers can expect “big changes” in “devastating” new episodes.

“Expect tragedy as well as adventure, that’s just how it goes,” Gatiss told Radio Times last November.

“Just because it’s in the stories, doesn’t mean it’ll happen in the series. There’s an awful lots of changes and an awful lot of places to go and things to do.”