'Doctor Who' series 11 news: Showrunner on why it did not cast a female lead sooner

Steven Moffat (L) introduced Matt Smith (R) as the Doctor, and saw him replaced by Peter Capaldi.Reuters/Fred Prouser

For the first time in the series' 54-year history, "Doctor Who" will undergo one of its biggest transformations: the Time Lord will regenerate into a woman. But what took the BBC show so long to cast its first-ever female Doctor? Three weeks before Steven Moffat is effectively done with the series, the outgoing showrunner finally answered that big question.

In an interview with Radio Times' December Magazine, Moffat shared how he toyed with the idea of casting a female Doctor himself. He admitted he considered replacing Matt Smith, the 11th Doctor, with a woman, but that obviously did not happen.

"We could have replaced Matt Smith with a woman, given that his Doctor was more sexless and less of a lad, but then I got obsessed with seeing Peter in the Tardis," Moffat explained.

According to him, he had no regrets over that decision, although he was worried about the series' upsetting "Daily Mail-reading viewers." He elaborated, "This isn't a show exclusively for progressive liberals; this is also for people who voted Brexit. That's not me politically at all - but we have to keep everyone on board."

That changes, though, with incoming showrunner Chris Chibnall. The English TV writer whose notable works include science-fiction series "Torchwood" and the ITV detective series "Broadchurch" is credited for breaking that tradition on the show; and despite not being able to achieve such big milestone, Moffat has nothing but good wishes for his team.

He believes casting a female Doctor is going to work. With more and more viewers demanding for it, he says that it is "absolutely the right choice" now.

Moffat has been the show's lead writer and executive producer for six series and eight long years. Earlier this year, he announced he is stepping down from his post after the last episode with Peter Capaldi's Doctor airs. Their swansong "Twice Upon a Time" is set to air at 5:30 p.m. on Christmas Day, Dec. 25, on BBC One.

Chibnall's debut series as head writer and executive producer will launch sometime next year with Jodie Whittaker in the lead role.