How long will Sherlock keep running?

Speaking ahead of the fourth series, set to screen early next year, Moffat admitted: "I don't know how long we can keep it going. I'm personally willing but I'm hardly the main draw.

"I would be moderately surprised if this was the last time we ever made the show. But it absolutely could be."

According to The Telegraph, Moffat suggested that Benedict Cumberbatch, who plays the detective, is now such a huge star that he only continues to do the show out of loyalty to fans.

He said he was "amazed" that the BBC had continued to secure both Cumberbatch and Martin Freeman, who plays sidekick Doctor Watson.

"They haven't needed to do these jobs for a very long time. They're coming back because they want to.

"I'm amazed that we've got this far. I thought that once they had got extremely successful, we would only get to do one more series."

However, he also suggested that the actors' love for the show means they could keep returning to it every few years, even if their schedules become super busy: "There would be nothing strange in stopping for a while. It could go on forever, coming back now and again."

So there's your answer: It could finish this year, or never at all.