Viv Groskop: Finally, a woman's been left in charge

Man the barricades! Grab your tin hats and gas masks! Adopt brace positions!

They said it would never happen. They said to believe otherwise was crazy talk. They said their brains were weak, their minds blurred by lactational insanity, their bodies broken by the demands of their curious internal lady clocks. But rejoice, because right here right now a woman, yes, a real live woman who can speak and walk and think and everything, is in charge of the country.

Tomorrow Theresa May, the seventh most senior Cabinet minister, takes her place at the pinnacle of government. Whilst David Cameron and Nick Clegg headed for Spain and William Hague finished his stint as acting head of the senior common room, the ministerial rota threw us a curveball: a girl. Imagine! One headline reads like a wartime air raid warning: "Theresa May to run the UK as Westminster empties." Man the barricades! Grab your tin hats and gas masks! Adopt the brace position!

To celebrate, rather than run for cover, feels bittersweet. A woman in charge shouldn't be noteworthy. This is the 21st-century. Thirty years ago we could perhaps dare to dream that in the near future we might view, say, a ferret running the country as some kind of anomaly. Women politicians would no longer be regarded as women politicians. They would simply be politicians. But, no, the woman is still headline news. Not the ferret.

(If anyone is training ferrets for coalition life, by the way, please get in touch. I'd be interested to know more. And if you are thinking at this point that Theresa May does look a bit like a ferret then shame on you. George Osborne wins that resemblance battle hands – or, rather, paws – down. Do ferrets have paws?)

For a Home Secretary to be at the helm is not news, of course. But a womb-owner has not been in full-scale charge since Margaret Thatcher in November 1990. When Harriet Harman took over for a few days in August 2009, within 24 hours she was accused of launching "a crusade against the British male". This is the climate we live in. According to a recent estimate, at the current rate of progress we will have an equal number of woman MPs by 2082.

By then I will either be dead or, worse, alive and a very demented 109 years old. Which is why even though I am no fan of the Home Secretary, I am personally throwing a very small street party to mark this moment. It's just me on my doorstep, eating a Rich Tea biscuit (we're in a recession), wearing leopard-skin mules (I have some pride). But it's a party nonetheless. You are welcome to pop in, Theresa. But you had better be wearing good shoes. And we definitely won't talk about politics.