Vanessa Friedman
Vanessa Friedman
ON THE RUNWAY

The seven-day British royal tour of India and Bhutan, which ended on Saturday, was an opportunity for many things, including benign national outreach and a show of good will between countries with a complicated history, as well as multiple photos featuring Prince William and Catherine, Duchess of Cambridge (the former Kate Middleton) on safari and at the Taj Mahal.

But it also raised the bar when it came to the modern art known as diplomatic fashion tradecraft, a.k.a. the use of a ceremonial political event to promote a specific national industry.

Michelle Obama may have elevated the role of clothes in political life to strategic tool, consciously choosing to wear pieces from emerging American designers, the better to use her position to raise their global profiles and businesses. Samantha Cameron, the wife of Prime Minister David Cameron of Britain, may likewise have chosen to support her country’s fashion talent, even going so far as to become an ambassador for the British Fashion Council. And Sophie Grégoire Trudeau, wife of Prime Minister Justin Trudeau of Canada, may have given Canadian designers a push during her recent state visit to Washington. But in India, the duchess took the approach to a whole new level.

An observer could have been forgiven for thinking practically all of Sloane Street had migrated to her suitcase.

Consider the list, in no particular order, of British brands she wore on the tour: Alexander McQueen, Emilia Wickstead, Jenny Packham, Topshop, Paul & Joe, Glamorous.com, L. K. Bennett, Mulberry, Rupert Sanderson, Accessorize/Monsoon, Russell & Bromley, Cassandra Goad, Temperley London, Kiki McDonough, Beulah, Pickett London, Jaeger, Really Wild and Penelope Chilvers.

The clothes encompassed the very expensive (McQueen, Packham, Temperley), fast fashion (Topshop, Glamorous) and the already worn (one McQueen outfit), and they included shoes, bags and jewelry — all chronicled obsessively (and daily) in the British and fashion news media. Many pieces sold out not long after the first pictures appeared.

The duchess also dipped a toe into cross-border sartorial diplomacy, wearing one dress by the Indian designer Anita Dongre and one by the Indian-American Naeem Khan, as well as looks from Anna Sui and Tory Burch, but a vast majority of her clothes were by British designers.

“I could not believe the local and global attention,” Ms. Dongre said on the phone from Mumbai, and her words were echoed by Mr. Sanderson in Britain.

The word “windfall” comes to mind.

Compared with William and Catherine’s tour of the East Coast of the United States in 2014 (remember that?), the India trip stands out as a much more powerful piece of sartorial messaging, in part because it so consciously embraced British fashion as broadly as possible, leveraging the duchess’s influence to benefit the elite and the mass ends of the market — big names and those on the rise.

Put another way: She may have gone on a tour of India, but, in doing so, she also took everyone who was watching on a tour of the British clothing industry. That’s quite a trip.