Doctor Who showrunner Steven Moffat has “not ruled out” the possibility of a return for River Song, although he admits he has reservations about any character spending too long with the Time Lord.

“It entirely depends on whether we've got a good story," said Moffat. "It's certainly not ruled out. I have a sort of worry about keeping anybody around in the Doctor's life for too long. Because he's the Man who Leaves. He's the man who outlives everybody: that's his story. In the end it's the boy in his box, and he's alone.

“In the end if we had a great story, we'd do it.”

One man who seems extremely keen to see Alex Kingston’s sassy Ms Song opposite Peter Capaldi’s irascible Twelfth Doctor is Moffat’s predecessor Russell T Davies, who apparently told him their encounter would be “a sex storm”.

Could he perhaps be the one to script the such a meeting? Only with a lot of editing, jokes Moffat, referring to Davies’s recent, rather risqué, Channel 4 drama Cucumber.

"I mentioned in passing to Russell that we were probably done with River,” Moffat told interviewer Jaci Stephens during a Bafta talk in New York earlier this month. “He said, 'You can't be done with River! No, no, no. Capaldi and Kingston, it's a sex storm!'

“So if you see an episode called Sex Storm by Russell T Davies in his post-Cucumber years... [there will be] lots of editing from me saying ‘We really can't do that, you've forgotten which show this is….’"

River Song died saving the Tenth Doctor in series-four episode Forest of the Dead but reappeared at various points in time in subsequent adventures. She was last seen as a digitally preserved consciousness that apparently bid a final farewell to the Eleventh Doctor in series seven finale The Name of the Doctor.

But as Moffat is fond of reminding us, this is Doctor Who, a show about time travel – anything can happen...

Series nine of Doctor Who is expected on BBC1 this autumn