In arguably the biggest (Sherlock) news of the century, Benedict Cumberbatch has announced that he and co-star Martin Freeman have signed up to make a fourth season of the BBC1 detective drama.

"We've agreed to two more series but I could get into trouble for saying that," revealed Cumberbatch at the South Bank Show Awards this afternoon.

"All I know at the moment is I'm doing these three [episodes of the upcoming series] and another three."

The star added that he would like to see the show continue beyond a fourth series but admitted it would depend on whether he, Freeman and co-creator Steven Moffat could find the time to do it.

"It just depends on Martin and I's availability, how long we can keep it going. It depends on Steven's ability. I'd love to keep it going."

Moffat is also showrunner on Doctor Who, while both Cumberbatch and Freeman are rising Hollywood stars. Freeman is Bilbo Baggins in Peter Jackson's ongoing Hobbit trilogy and Cumberbatch – as well as voicing characters in the same movies – is about to hit cinema screens as the enigmatic villain of Star Trek sequel Into Darkness.

Filming of Sherlock season three begins on Monday (18 March) with the series expected to air in the autumn.