Why Diana's style Queen (again): from pie-crust collars to see-through skirts, the 'Shy Di' look is fashion's hottest trend

To women in their 50s like me, the latest offering from Marks & Spencer will provoke a frisson of familiarity.

Modelled by socialite Alexa Chung as part of a new collection she’s designed for the High Street chain, there is a blast from the past: a ruffled, pale pink, pie-crust collar blouse that has come direct from the Eighties. All she needs is a copy of the Sloane Ranger handbook, blue eyeliner and a glass of sweet German wine to complete the look.

These blouses were the upper-class gal’s answer to everything that had percolated from London youth culture — the costume dressing of the New Romantics toned down for boarding school or the office.

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Princess Diana, pictured circa 1980, opts for a dramatic pie-crust collar, while Alexa dons a similar look as she announces the launch of her M&S archive range

Every woman back then owned one of them (usually from Laura Ashley or, indeed, M&S, where they were the biggest seller in 1982). And no wonder — we were trying to get the look of the woman we all wanted to be: Princess Diana.

Now, she’s back in fashion. Move over, Kate! As I wrote in my new column in the Mail’s Inspire section last week, look around the High Street and the clothes worn by the Eighties Diana are everywhere . . .

On celebrities, on the catwalk, on the High Street and — no doubt — about to be worn by you and your daughters.

Forget-me-not: Diana's bow is adopted by X Factor's Cheryl Fernandez-Versini

Remember those fragile floral midi-dresses and skirts — see-through when back-lit (as 19-year-old Diana found to her cost when caught by photographers in compromising sunlight)? Now they’re being worn by model Poppy Delevingne to fashion week (and are as see-through as ever).

Then there’s those frilly blouses that became her thing — high-necked, modest, yet tantalising the onlooker to guess what lay beneath. They are now back in shops, from River Island for £35 to H&M for £25 — Dolce & Gabbana even has a version.

Even those huge shoulder panels on day-dresses are making a return, cascading from high fashion to High Street.

The look isn’t smouldering Diana the Divorcee, though, but rather Shy Di, the innocent nursery nanny who became a blushing young princess.

So WHY is it all flooding back? Well, fashion is cyclical, of course: we’ve just had a season that was obsessed with Seventies patterns (paisley), fabrics (suede) and colours (mustard).

Sheer flair: The famous sunlit photo of a shy nursery school assistant is evoked by Poppy Delevingne for London Fashion Week

The early Eighties is the logical next step: a return to romance and femininity. Already, you can see it in the florals, chiffons and purity of shapes on the catwalk.

The other clue is that today’s young tastemakers don’t remember the first time round, so it all seems fresh and new.

No wonder the first thing Alexa Chung dug out of the M&S archive in Leeds was the pie-crust blouse with a big ruffle on the shoulders, first released in 1982, the year Prince William was born.

He’s now 33 — exactly the age of all the women and designers who are looking again at Diana and thinking: ‘Gosh, how great!’

Blue Jean blueblood: Diana's high-waisted style finds favour with Gwyneth Paltrow

The huge, inflated leg o’mutton sleeves of Diana’s 1981 David and Elizabeth Emanuel wedding dress and innumerable state-occasion evening gowns — they’re back, too, pushed by young designer J.W. Anderson and worn by the editors going to Fashion Week. And then there’s peplums, polka dots, dungarees and skirt suits, too.

Off-duty Di is with us as well. Every trend-conscious woman is busily ditching her skinny jeans and staging a wholesale rush to high-waisted, tapered-leg Eighties jeans — the very item Princess Diana was snapped in, hanging out with Fergie, at all those polo matches.

You can take it right down to the detail. Wrapped-leather tie belts. Low-heeled Eighties pumps. The little black ribbons Diana wore tied in a bow under oversized collars.

Spot the resemblance: Diana's formal elegance at the Epsom Derby is echoed by Amal Clooney

It might stop at the side-swept hairdo Richard Dalton created for Diana in her early years . . . so far. But I wouldn’t be at all surprised to see that being echoed in this summer’s fashion shoots.

What they’re homing in on isn’t the sleek, put-together, tailored image Diana evolved with designer Catherine Walker, fashion house Versace and the hairdresser Sam McKnight in her 30s.

This look isn’t the confident, movie-star glamour we saw in Mario Testino’s Vogue and Vanity Fair shoots. Oddly enough, it’s the Duchess of Cambridge who has assimilated that polished, assured, faultlessly groomed, camera-ready Nineties Diana template — and has, whisper it, made it rather safe.

Starstruck: Even outrageous pop star Lady Gaga borrowed some of Diana's elan in this plunging black dress

Her version of a non-controversial royal look — honed to her formula of fit-and-flare Sarah Burton coat-dresses and long Jenny Packham and Alice Temperley evening dresses — is consciously calculated to avoid getting involved with too much fashion.

I’ll bet the last thing we’ll see Kate Middleton in is a Shy Di pie-crust blouse and a see-through skirt.

But that’s because Kate won’t take risks with fashion in the way Diana did. It was a way of expressing herself, of giving the public a glimpse of the woman behind the royal title. No wonder we fell for the sweet and awkward girl who made up her own look and triumphed. Once Diana got into her style, what woman back then didn’t want to emulate the People’s Princess?

Now a whole new generation is discovering it for themselves. All I can say is: lucky them. Go ahead, have fun with it. 

Dungaree duo: The Princess dressing down for polo, and singer Rihanna giving the same look an outing