Benedict Cumberbatch '˜thrilled to be back' filming fourth series of Sherlock

Benedict Cumberbatch said he is 'thrilled to be back' as filming for the fourth series of Sherlock is under way.

Mark Gatiss tweeted a photo of himself teasing the series. Picture: BBC

He returns to the popular BBC One show in the leading role, with Martin Freeman as his trusty assistant, Doctor Watson.

Fans will see the famous detective “back on British soil” and Doctor Watson will tackle a new challenge: parenthood.

Cumberbatch said: “I can’t wait for everyone to see season four. But you will have to wait... though not for long... And it will be worth it.”

The series will return with three feature length episodes, the first of which will be directed by Rachel Talalay. Her previous TV credits include Doctor Who, The Flash and The Wind In The Willows.

In a joint statement, co-creators and writers Steven Moffat and Mark Gatiss said: “Sherlock series four - here we go again!

“Whatever else we do, wherever we all go, all roads lead back to Baker Street - and it always feels like coming home.

“Ghosts of the past are rising in the lives of Sherlock Holmes and John Watson bringing adventure, romance and terror in their wake.

“This is the story we’ve been telling from the beginning. A story about to reach its climax”.

Gatiss posted a teaser video on Twitter of himself holding a director’s clapboard, emblazoned with “Sherlock IV”.