Unless you’re a professional dressmaker, you’ve probably never given pockets a great deal of thought. But maybe we’ve all been underestimating their psychological importance. My suspicions were aroused when Luella Bartley was explaining what goes through her head when designing those little prom-type bouffant dresses that always crop up in her collections – pockets, and the way they make a woman stand when wearing a dress.

Bartley thinks a slouchy insouciance is the key accessory when you’re wearing something traditionally formal these days, and that pockets give a woman the wherewithal to display just that. Designers talk like this, and it’s easy to take them out of context and make them sound ludicrous. But she’s right. Not striking that right note of relaxed indifference can leave a woman looking stiff as a show poodle, or one of those poor, rabbit-in-the-headlights red-carpet celebrities. And that’s a sad look in this day and age.

A few weeks later, I’m looking at a chic new label in Paris called Kinder (think sportive, lightweight Chanel with dip-dyed jackets that fashion editors were busy placing personal orders for). Its designer, Paolo Aggugini, is big on construction, tailoring – and pockets. He thinks they’re the marker between something so-so and something modern with attitude. It’s the Coco Chanel thing – think of that famous Man Ray portrait of her perched on a pouffe, faux pearls winking, fag providing atmospheric wreaths of smoke. This was the Thirties. Chanel’s hands are thrust into her pockets – a defiant pose that still communicates casual elegance today. Unlike the cigarette.

Lucinda Chambers, the Vogue fashion director who consults for Marni, recently mentioned that Marni rarely produces a dress without pockets. Having a pocket gives a woman something to do with her hands and helps her confidence, even if she never uses it. What is this? A conspiracy of pockets or a groping towards the kind of clothes that make a woman feel comfortable today? When Coco inserted pockets in womenswear it was quite revolutionary and part of an aesthetic that pilfered ideas from men’s clothes. Men and women had both worn detachable pouches on belts until the end of the 18th century, when pockets finally became part of the construction of men’s clothes.

Women had to wait another century for such liberation. Even then it was slow. In the Thirties, as a junior on Harper’s Bazaar, Diana Vreeland had the idea to dedicate a whole issue to pockets, in the belief that it would encourage designers to create clothes that would liberate women from their handbags. “Diana,” she was admonished by a senior editor, “are you aware just how many millions our handbag advertisers bring to the magazine?”

With the outsize bag dying, pockets are getting bigger. They’ll be ubiquitous by summer. But there’s nothing to stop us getting our hand in, so to speak, now. It makes a difference where they’re placed: on the legs and you’re a wannabe GI Jane in combats, on the thighs and you risk looking like a GI Shane. On the waist, and they’re there just for prettification. Pockets that don’t work are a travesty. No, the secret to slouchy chic is pockets on the hips that you can get your hands in. It’s that simple.

Times recommends

• How I lost the gift of joy for a while
• How to get Coleen Rooney's post-baby body
• The A-Z of winter style rules