He’s headed up the Doctor Who creative team since taking over from Russell T Davies in 2010, but when lead writer Stephen Moffat departs the show after series 10 next spring, he reckons it will be for good.

Speaking to students at the Oxford Union last week, Moffat said, “I think as much as I hate to concede it and I’d like to have Russell write for me, this is probably it for me – once I’m done, I’m done.”

Although he loves the show, he said, “I’ve written a hell of a lot of Doctor Who. I’ve written more Doctor Who than anything else, and I’ve written more Doctor Who than anyone else has ever written. It feels as though, in my limited time on this Earth, I really should start focusing on something else. It’s not that I’ve lost love for the show at all, but I think it’s time for Doctor Who to have something new, as well as me.”

Moffat has been a Doctor Who fan since his childhood, and has been writing short stories and episodes of the space traveller’s adventures since 1995. His first contribution to the 2005 reboot of the show was the haunting ‘Empty Child’ two-part story, in which a child with a gas mask repeatedly asks Ecclestone’s Doctor “are you my mummy?”

But it wasn’t until 2010 that he became showrunner, involved in the casting of Matt Smith as the Eleventh Doctor and then Peter Capaldi as the Twelfth.

Moffat conceded that he tried hard to persuade Davies to continue writing for the series after his departure, telling students that he was “so close…we had storylines and everything”, but that workload proved too much for his predecessor, who since leaving has been involved in Channel 4 and E4 series Cucumber and Banana and the BBC’s adaptation of Shakespeare’s A Midsummer Night’s Dream.

Moffat will also be kept busy upon his departure with his BBC series Sherlock expected to continue into a fifth series – but first, he’s got a Christmas Day Doctor Who special and a final series airing this spring. When asked what viewers could expect from his swansong episodes next year, he told students that “the Doctor will reliably save the day, there will be vague speeches, there will be an epic amount of urgent standing, and you will fall in love with Pearl Mackie”.

But first, Christmas – and, according to Moffat, it’s one of those episodes where everything just fell into place. “Some days, it’s quite lucky. Everything seems to work and you think ‘this episode is a cracker’. I slightly feel that about the Christmas Doctor Who, I think it’s one of the ones where everything just seemed to click into place.”

And despite coming to the end of his role at Doctor Who, his second BBC commitment looms large. So who would win in a battle between Sherlock and the Doctor?

“In the case of that slight improbable event, I suppose the Doctor would be better. But, you know, Superman would be pretty good, too.”