Ahead of the second series, Moffat told BBC News that there was “no guarantee” of any Sherlock series past the impending second. He revealed on Sunday night though his comments were a tad misleading, Tweeting: “Of course there’s going to be a third series – it was commissioned at the same time as the second. Gotcha!”

Co-creator Gatiss also took to Twitter to reveal how Sherlock, which stars Benedict Cumberbatch and Martin Freeman, will return for a third series of mysteries. “Gotcha! And of course there will be a third series,” he revealed also. 

Series two’s concluding third episode was watched by an audience of 7.9million, compared with the 10.7 million who tuned in for the opening first episode at the start of the month. 

Both Freeman and Cumberbatch have top Hollywood projects on the go – Cumberbatch has been cast in JJ Abrams in-production Star Trek sequel, due for release in 2013, and Freeman stars as the diminutive hobbit Bilbo Baggins in Peter Jackson’s The Hobbit: A Unexpected Journey, the first of two Hobbit films due out in December this year. 

The BBC’s Sherlock has been a critical hit since it premiered in 2010, fusing Sir Arthur Conan Doyle’s famous detective tales with a contemporary spin.