Benedict Cumberbatch says he is ‘genuinely thrilled’ to be back working on Sherlock series 4, which has just begun filming.

Series four will consist of three feature-length episodes and star Benedict added: “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.”

Once more Sherlock will be back once more on British soil, as Doctor Watson and his wife Mary prepare for their biggest ever challenge – becoming parents for the first time.

Co-creators, writers and executive producers Steven Moffat and Mark Gatiss (pictured) 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.”

The new series will be directed by Rachel Talalay, who has previously directed Doctor Who, The Flash and The Wind In The Willows.

Sue Vertue, executive producer, Hartswood Films, said: “It’s taken a while to gather everyone together for series four, but I can confidently say I think it will be well worth the wait!”

Sherlock: The Abominable Bride, which screened on New Year’s Day this year, was the most watched programme over the festive season with 11.6 million viewers and the highest ever audience share for a Sherlock episode.

No word yet when Sherlock series four will screen on BBC1.