Liz Hoggard: Never get engaged to a prince after three days

In three weeks' time, Grace Kelly's wardrobe goes on display at the V&A. You can cut out paper dolls of her wedding dress, watch Rear Window on constant loop. Perfectly sensible women will queue to swoon over her Hermès bag. Even the current spring/summer collections are full of her influence. But why does she matter so much to women?

I hesitate to mention it but on screen she did that slutty-pure thing brilliantly. Think of her, half-cut in High Society, juggling three men. Or ignoring Cary Grant all night in To Catch a Thief; then the minute her snooty mother disappears, snogging him passionately.

And not just on screen. Despite that glacial blonde perfection, there are rumours she slept with 14 lovers including (the very married) Bing Crosby, and William Holden. The official Hollywood version got rewritten – after marriage to a Prince and genteel retirement in Monaco. She didn't do subservience. She embodied sexual desire, while looking exquisitely fresh. She refused to let the movie moguls bully her. An ex-convent girl from Philadelphia, born to immigrant parents, she only starred in 11 films over six years, but helped change the stuffy rules about how actors ought to behave. She battled racism, making a close friend of Josephine Baker.

Fifty years later, her screen presence seems incredibly modern. Part of the sadness is that her career stopped. In 1955's High Society she's already wearing Rainier's ring. At the Royal Palace in Monaco, which I toured years ago, she looms out of family portraits, strained in a kaftan, drink by her side. No wonder she and Diana, Princess of Wales bonded. Life in the gilded cage took its toll. Memo to self: never get engaged to a prince after three days. There's the note to Hitchcock where she hints at the reasons she had to leave the set of Marnie. Then came that terrible, fatal car crash in 1982.

Last weekend I spent the night at Mayfair's Connaught Hotel, which used to be her London home. Book in for their Style Icon Weekend and the butler will take you to on a private visit to Balenciaga (very Grace) and serve you cocktails inspired by different stages of her life, including "Hollywood Star", "Beloved Princess" and "Royal Bride". It ought to be revolting, but actually it's heaven. Catnip for mothers and daughters, who (whisper it) don't have quite enough in common any more. Because retro femininity matters. It's our guilty pleasure – hence our love of Mad Men.

Women love to bond over emblems of troubled femininity that would suffocate them in real life. We should be analysing the gender pay gap, but instead we sit mute with love, watching Grace's swimsuit in To Catch a Thief. What she had was mystery – and sexual elegance. The cut of her gowns was intellectual. And yet she was too tall, shortsighted and battled with her weight. She had daddy damage (he always preferred her sister). Her Cinderella transformation is our victory.

The ultimate lady, she got away with some very unladylike behaviour. No wonder that Mika, the great polysexual pop artist, immortalised her in a song. As Grace herself declared: "I'm basically a feminist. I think that women can do anything they decide to do."