The jeans lessons every woman can learn from Sarah Jessica Parker.

Quick quiz: Pick the odd one out.

A) Kendall Jenner, the face of Calvin Klein Denim;

B) Hailey Baldwin, the face of Topshop Denim;

C) Karlie Kloss, the face of Express Denim;

D) Sarah Jessica Parker the face of Jordache Denim.

If you said A) Hailey Baldwin because her parents are real celebrities you're funny – but wrong.

It’s SJP. She’s 50. Denim labels usually hunt the young. Jenner is 19, Baldwin 18 and Kloss 23 (she's getting long in the tooth). And if you can remember back that far, Brooke Shields was 15 years old when she whispered to the camera "nothing comes between me and my Calvins". There's something about the pairing of rough denim with fresh faces that marketers find irresistible.

But fashion icon Sarah Jessica Parker has bucked the trend for having models younger than the cotton and six percent nylon they're wearing and fronted a campaign for Jordache, an American clothing company popular in the late 70s and early 80s.

SJP wore their jeans the first time around and she's back in them again. And Jordache is lucky to have her.

This is SJP. A woman who dresses in two states: Met Gala who-doesn't-love-a-Chinese-flame-Haute-Couture-head-piece-worked-back-with-a-poppy-flower-cape-ensemble or Manhattan school-run chic - with jeans being her favoured item.

Her downtown casual look; the way she cuffs, layers, her shoe choice, the size of her take-away coffee is scrutinised just as much as the OTT gowns of opening nights. If there wasn't already a 'J' in there, denim would be her middle name.

When it comes to this latest campaign look past the airbrushing. Look past the cat poses. I know it's been said "she's a smart, successful woman why is she bending over a table like that"? Because it's a jeans campaign. I know she's 50, but what do you want her to do? Have the campaign shot around her playing Sudoku and shopping for a hearing aid?

What is really going on here? A 50-year-old woman heading a jean campaign? It's important. Not just because she is twice the age of most models in denim campaigns, but because, in a strange way, this is about attitude. A don't-tell-me-what-I-can-wear attitude. SJP is 50 and wearing skinny jeans. Women don't just wear "mum jeans" when they grow up. They wear skinny ones and ripped ones and ones with baggy crotches. In short, they wear jeans some whisper they are "too old for".

I saw a woman, who must have been in her 60s, the other day in a pair of skinny dark denim jeans with a long, white, crisp collared shirt on top, brogues on the bottom. It's how you wear them not what you wear. She looked fabulous.

"My only rule is not to wear the ones that don't look good on me," SJP said about wearing skinnies in the campaign. "I wouldn't even be aware of opinions on a rise, or a waist, or skinny-leg versus drainpipe jean ... wear the ones you love and make you feel good."

It's easy to wonder whether we have become too old for something. Too old for long hair, too old for minis, too old for spaghetti straps because good girls have always been told to "dress appropriately". And most women have that good girl still inside her. The question should be not about our age setting the parameters for what we wear, but our attitude and a mirror.

Have a look in the mirror. If it looks good and you feel good, wear it. If it doesn't look good and makes you uncomfortable don't. SJP breaks the fashion rules all the time. Don't tell me what I can wear.