What William Hartnell looks like now is UNBELIEVABLE...

YES, that's right, in a shock twist there's actually some clickbait out there which turned out to be ahead of the curve.
All those times you were invited to click on shitty articles about the fact that actors age like everyone else were finally vindicated when the principle was applied to Time Lords. It turns out that the Edwardian old man from the 1960s would arrive in 2017 as a thirty-something woman from Yorkshire. And all hell has broken loose.
I tend to think that people making the most noise about the fact that Doctor Who has cast a woman - whichever side of the debate they're on - won't actually be avid viewers of the show. 
Do I believe that Richard Littlejohn - surely now hammering at his keyboard about political correctness gone mad - broke off from watching Episode 3 of The Daemons to pen his diatribe? Absolutely not. Would many of those Millennials who are busy tweeting that this is "exactly what the show needs" be able to pick the Mondasian Cyberman from a line-up? Unlikely.
That's not to say only hardcore Whovians should have an opinion, but it does suggest to me that there is a lot of point scoring going on. A lot of the regular viewers - be they young kids or young kids at heart - mostly just want the programme to do well. And not be cancelled, obviously, because that's the underlying fear that stalks any sci-fi fandom.
Personally I find people who shriek they'll never see the show again more than a bit hysterical (and they will by the way, if only so they can go online and write about how awful it is). That said, those who have posted comments along the lines  of "I'll actually watch it now" also concern me. Is claiming you can't relate to a show because the main character's a man any more logical than cancelling your subscription to Doctor Who Magazine because the Time Lord is now a Time Lady?
Full disclosure, back when Matt Smith announced his departure I wrote about possible replacements and for me the default for the character was 45ish and male. I didn't put the likes of Tilda Swindon at the top of my wish list for the same reason I didn't imagine the Doctor suddenly speaking with a Midwestern drawl or pulling on a pair of trackie bottoms.
As time has gone on, I've had to think about whether a series which is fundamentally about renewal needs to be more radical. Maybe all of time and space needed opening up a bit. Three things have perhaps shaped my current view. 
One, it has now been firmly established in show that Time Lords can change gender when they regenerate. And what is canon is king as far as I'm concerned. 
Second, I remember how chuffed I was when I found out that Christopher Eccleston would be playing the part in his native Mancunian accent. In an interview he said he wanted to send a message that people don't have to speak "proper" English to save the universe. If young girls are similarly inspired by a female Doctor then that's got to be a good thing. Lots of planets have a North, but pretty much all have a gender balance.
Finally the decision a few years back to cast Michelle Gomez as the Master was inspired and properly convinced me that when casting someone with two hearts it didn't really matter how their Chromosomes add up. 
So while I was never comfortable with the notion that if this next Doctor wasn't a woman it would be a patent insult, I also feared some in the "no" camp may be the sort to question whether women should be physicians full stop, never mind one from another world. For me, personally, the most important thing was finding the right person for the part.
And is that Jodie Whittaker? If I'm honest I'm not immediately sold. She seems to lack that difficult to define Doctorish quality which says to long-time fans "this is going to be okay." Matt Smith - all twitching fingers and chin - definitely had it. Peter Capaldi, who strode on stage clasping his lapels, also oozed that offbeat charm.
That's not to say first impressions count for everything. I found Capaldi had an up-and-down first series, while Tennant - whose initial casting left me cold - took to the part very quickly. How will Whittaker fare. Only time will tell. But I obviously wish her well... Roll on Christmas.