Is one of the most formidable partnerships in fashion about to break up?

It was Burton, too, who introduced the Princess to Paolo Roversi, whose dream-like fashion photography for Vogue is a far cry from conventional royal portraits. Catherine, who knows a thing or two about photography, liked what she saw and it was Roversi who took the 40th birthday portraits of the Princess wearing Burton for McQueen. The reception was mixed, but the Home Counties girl who used to dress in fraying Zara had evolved into a global icon.

Behind the scenes, they have plenty to talk about. Both are mothers to three children. Burton, 49, has three daughters – 10-year-old twins and a seven-year-old. She lives in St John’s Wood, the smart north London postcode of white stuccoed terraces and red-brick mansions that look like mini-Kensington Palaces. Like the 41-year-old Princess, Burton loves the British countryside and every season would lead her design team at McQueen on expeditions to ever more remote corners of the British Isles, where they would study ancient textiles and techniques.

It’s a far cry from Paris, where the McQueen shows take place twice a year, and anyone paying close attention might have spotted that herein lay a possible dissonance. While Burton eventually began granting interviews to a handful of journalists, it was always clear she found them stressful. The exquisite 3D paper dolls she made to represent every design she was working on were testament to her passion for the nuts and bolts of her job. But pose an unscripted question about anything other than technique and you’d be met with a panicked eye.

Burton admitted that she had been forced to confront her tendency to introversion. “There have been times when, if I could have disappeared from this industry, I would have,” she said. “I had to battle with it. I don’t look like a fashion person. I’m not cool, and I always just loved people who are good at what they do.”

Off the record she was chatty and dressed habitually in a pair of old Levi’s, a shirt (not tucked in) and with a black blazer invariably over the back of a chair somewhere. She seemed to enjoy doing one-on-one previews before the shows in Paris. But perhaps that wasn’t the case. Post pandemic, the previews mostly stopped. The interviews have become vanishingly rare.

She will have more family time initially because while the official announcement from McQueen came with fond words from François-Henri Pinault, chief executive of Kering and her ultimate boss, Gianfilippo Testa, McQueen’s current CEO and Burton herself, there is no hint of where she may go next.

On the other hand, all parties might be ready for a change. The clamour for Louis Vuitton accessories after Pharrell Williams’s debut menswear show for the brand has reminded executives everywhere of the power of loudhailer tactics. And while there can be no better advert for traditional glamour than the princess, other brands generally have a number of ambassadors who can appeal to different tastes.

“Kate’s such an icon but it’s limiting,” says Fflur Roberts, head of luxury at euromonitor.com. “Not everyone wants to dress like her. Kering may want to diversify now. To be a big player, McQueen needs to amp up its fragrances and launch make-up. It’s going to be so interesting to watch.”

Even if a Pharrell-like appointment as her successor is unlikely, Pinault may want someone who engages more with the impetus of fashion. Close Burton observers think she may step back from the coalface for a while and turn her energies to helping young designers and artisans – possibly through Sarabande, the charitable foundation launched by Alexander McQueen in 2006 to do just that.

There will be tears at her final show in Paris in three weeks. They were always moments of luminous beauty. But there will also be anticipation – who will replace her and take McQueen to the next level as a true global super brand? And as for Catherine? Burton’s departure is a sartorial blow, especially after the triumph of the white dresses she and Charlotte wore to the Coronation. It was Burton, too, who made the connection with Jess Collett, the milliner who designed those scene-stealing non-tiara tiaras.

Loading

So who will dress Catherine now? She won’t be entirely bereft; Erdem, Roksanda, Roland Mouret, Emilia Wickstead and Jenny Packham are among the British-based contingent who have done her proud, even if none has such close ties as Burton. Besides, initially, it’s almost certain Burton will continue to advise her from the wings, according to Roberts: “In the short to medium term, Burton’s relationship with the royal family will continue because it’s more about her than the brand. She’s so trustworthy and consistent.” There is a real possibility that Burton could continue to dress the princess under her own private label, too, if she chose to follow that route.

The princess has acquired deep reserves of insight into what looks good – as well as a vast wardrobe. When she stepped out last week on an official visit to a prison it was business as usual – in a Burton for McQueen trouser suit.

The Telegraph, London

Start the day with a summary of the day’s most important and interesting stories, analysis and insights. Sign up for our Morning Edition newsletter.