Okay, so she never got to be Queen. Missed it by a whisker. Coming second has its advantages though, as Prince Harry will tell you. It allows a freedom you’d never have if you actually had to be monarch.

Princess Margaret could be wild. She could break the rules. She could smoke and go out with commoners. She could wear foreign clothes and go out to nightclubs.

Okay, so a few eyebrows might have raised when she wore a strapless gown  (it’s rumoured Her Majesty insisted on straps being sewn into one of Margaret’s frocks), but generally life as second-sister had serious perks.

Those perks often involved fashion and Margaret is, without doubt, the most stylish royal we’ve had in recent memory. And yes, I do count Diana in that. I’ve never understood the passion for Diana’s dress sense – I loathe it pretty much universally as either severe tubes of fabric that made her look like a pillar box with shoulder pads or oceans of 80s flounces and frills  our of a 3 year-old’s dressing up box.

Kensington Palace’s new exhibition Fashion Rules: Restyled follows frocks belonging to Diana, Princess of Wales, as well as Her Majesty the Queen. For me, though the main reason to visit is to pore over Margaret’s fabulous sense of style.

In a time just after the second world war, Britain was still rationing pretty much everything. Christian Dior’s New Look was shocking enough, but to see a member of the Royal Family wearing a dress made from so many acres of fabric it needed a crinoline to hold it out was really something else.

This stripy number by Norman Hartnell may at first look more like one a Victorian princess might have worn, and there’s more than a hint of ‘Little Women’ about it (no coincidence, I assume, that it’s from the same year the Hollywood movie was released) but it is, in fact, one of Margaret’s dresses.

It’s not a vintage look trending today, but the workmanship in it, the superb use of the stripes and attention to detail sends this into the A-list.

Much more likely to appeal to the modern vintage lover is this 1953 evening dress Margaret wore to see the theatre show Guys and Dolls in 1953.

Also by Norman Hartnell, the thing that really stands out is the extraordinary lace detail. It’s a look that’s been copied so often with cheap lace you really have to see this in the ‘flesh’ to really get how exquisite it is.

Something else about this exhibition is that you can get a good look at the inner construction of these garments. They might have been strapless, but these frocks weren’t going anywhere. There was more scaffolding on them than the Empire State. You can walk right round most of the exhibits- and those you can’t have  lots of mirrors so you can see the backs of the garments.

Take this cocktail dress, from 1951, by Jean Dessès. In deep, rich blue, it was strapless, but the princess also wore it with an organza jacket at Ascot in 1953. A glance inside shows an inner bodice so bloomin’ tight the outer one could appear to be almost ‘loose,’ despite its being for a rumoured 18″ waist.

As she wasn’t monarch, Margaret was under less pressure to ‘buy British’ and she often went to the French couturiers for inspiration.

Christian Dior was one of her favourite designers. This exquisite chiffon cocktail dress was featured in Vogue as part of Dior’s Sinuous Line, and originally had a rosebud pattern. The princess ordered it in pure white. I’m using my own picture here as it quite rightly gives the dress an ad-hoc halo. It deserves it. But just look at the detail:

You really need to see this up-close. No wonder it was one of the princess’s favourites.

It’s one of my favourites, too, but not my absolute fave. Before we get to that, though,

Margaret’s accessories were the talk of Society. Her fabulous collection of sunglasses was as chic as Audrey Hepburn’s and this little fur wrap is so chi-chi I want to cry. I try not to think of the little furry animals that died in its making.

One of the things I think of most when it comes to Margaret (apart from the ever-present fag; newspapers loved snapping her with a ciggie in her hand) is her headscarf collection. There are several scarves on show at Kensington Palace. This one was specially designed by Christian Dior for the princess as a thank-you for patronising his style.

 

I’m not entirely sure why they included one of Margaret’s later frocks, which looks a bit like a panto costume. Presumably for completists, though it does at least have some nice beadwork and lace-work.

 

And so, at last, to my favourite frock in the show, by some distance.

Isn’t this the most gorgeous, elegant dress ever? In heavy cream duchess satin, with turquoise beading and bust detail, then with a truly understated sash. Again, thanks to being able to walk right round it, you can see inside the garment and see how the piece was constructed.

This is an exhibition for fashionistas and dressmakers as well as Royal watchers. I suspect most people will be there for the other two, more famous Royal women, but for me it is Margaret’s dresses that make Fashion Rules: Restyled truly stand out.

Fashion Rules: Restyled opens at Kensington Palace, 11 Feb, 2016, entry included in the main palace entrance ticket.