Sienna Miller is, at this moment, sunning herself on the deck of a yacht off the Amalfi coast, wearing nothing but some teeny bikini briefs and a come-hither smile. Or maybe she is house-hunting in LA. It’s hard to keep up, but one thing’s for sure: she’ll be steering clear of the UK for a while, because, the way things are going, if she shows her face here she’ll be egged, if not stoned.

Sienna (deep breath) is having an affair with an actor called Balthazar Getty. It’s official, thanks to some long-lens evidence, and this is the final nail in the coffin of that minx home-wrecker, because Getty is married and the father of four kids. It’s not an enviable job, defending a woman for sleeping with a married man, but someone’s got to do it — because this is just another chapter in the relentless vilification of Sienna. It’s merely the excuse that the legions who have already condemned her “lifestyle” were hoping for.

Let’s recap the evidence against her so far. Sienna (single, young, childless, free to come and go and take off her top on a yacht or in a private hotel room) had, up until a few weeks ago, done nothing more scandalous than date a few single — repeat, single — actors and dump Rhys Ifans. But never mind that. She’s a serial shagger! And now look what she has gone and done. Note that nobody seems interested in the men in the picture. Do we care how many hearts Rhys has broken? (Well, you never know.) And what about this Balthazar bloke? Is he a paragon of virtue among Hollywood actors?

Was he training for the priesthood? Literally nobody cares. He is the one with the four children and the wife and everything to lose — but there is only one home-wrecker in this scenario and it’s that slut Sienna. Just as Angelina was the downfall of poor, hapless Brad, and the girl who comes between Prince William and Kate (here’s hoping) will be branded a near-engagement-wrecker.

In this country, we can’t handle women having the same sexual freedom and confidence as men. Carla Bruni had an affair with Mick Jagger when he was married to Jerry Hall, and was a self-confessed polygamist, but that just added to her exotic charm, because she was doing her stuff in France. Sienna, on the other hand, is not married to a high-ranking politician or beholden to anybody. She can do what she likes, but that seems to be where our problem with her starts.

Four years ago, Sienna was on track to become a young wife living in a big ego’s shadow, before she picked herself up, dusted herself off and decided to explore the world just like a man might. Would it be too much for us to celebrate that?

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