Here’s how the show prepared the way for the Doctor’s gender change:

It was Tom Baker who first floated the idea of a female Doctor, back in 1980. Leaving the role he declared, “I wish my successor, whoever he or she might be, the best of luck.” It was a prank to bait the tabloids, but the debate had begun…

In 1986 series creator Sydney Newman pitched a reboot with a female lead: “I want to avoid a flashy Hollywood Wonder Woman, because this kind of heroine with no flaws is a bore.”

Joanna Lumley became the first woman to play the Doctor in The Curse Of Fatal Death, a 1999 Comic relief skit by an up-and-coming Steven Moffat.

Arabella Weir was an alternate Doctor in 2003 Big Finish audio drama Unbound: Exile. We’re told a Time Lord can only switch gender if the previous incarnation has committed suicide.

Some claim BBC Controller of Drama Commissioning Jane Tranter eyed Judi Dench to lead the show’s 2005 revival. Not so, russell T Davies tells SFX: “It was a one-liner, a good soundbite. So no, we didn’t consider a woman back then. I wish we had now, it’s so exciting.”

2009’s “The End Of Time Part Two” acknowledges the possibility on screen. “I’m a girl!” cries Matt Smith, mistakenly. 2011’s “The Doctor’s Wife” references a gender-hopping Time Lord named the Corsair while 2013 minisode “The Night Of The Doctor” sees a dying Eighth Doctor offered a choice between “Young or old, man or woman” by the Sisterhood of Karn.

Missy is the first Time Lord we meet reimagined as a woman. “Some of us could afford the upgrade,” states The Artist Formerly Known As The Master. The first male-female regeneration we actually witness is in 2015’s “Hell Bent”. “Back to normal, am I?” asks the General, now played by T’nia Miller. “The only time I’ve been a man, that last body. Dear Lord, how do you cope with all that ego?”