As for Mr. Sikhounmuong himself, he has turned Madewell into a roaring success, albeit one that started from a pretty small base. And, pointedly, like so many current design successes from Maria Grazia Chiuri and Pierpaolo Piccioli at Valentino to Alessandro Michele at Gucci, he is not only an in-house appointment as opposed to an outside star, but he started his career in accessories (at J. Crew).

For the past two days, Michelle Obama, her mother and her two daughters have been in London promoting the Let Girls Learn initiative and doing some outreach via Britain’s fashion industry on the side. It’s been a pretty effective demonstration of diplomatic multitasking.

Tom Mora, the former head of women’s design for J. Crew, is “leaving the company,” according to a news release, and Somsack Sikhounmuong, the current head of design for Madewell, has come in. Jenna Lyons, president and executive creative director of the J. Crew Group (which includes Madewell), the designer-over-all, is staying exactly where she is.

Put another way: A head has rolled — but not the top design head. And it’s the first time I can remember that the head of women’s wear, normally a behind-the-scenes position, has been put smack in the red-hot spotlight, a marked shift in strategy for a fashion brand of any level.

It’s hard to know now (the brand isn’t saying anything beyond what was in its announcement). What we do know is that Mr. Sikhounmuong grew up in Toronto, collected Vogue growing up, graduated from Parsons School of Design in New York in 1999, and worked briefly for Diane von Furstenberg before joining J. Crew in 2001 in the handbags department. He ultimately became director of accessories before moving into clothes, and jumping to Madewell in 2012. Now he’s back home.

It’s almost as if she hasn’t played a part at all, to the extent that, in the news release announcing Mr. Sikhounmuong’s appointment, there was a quote from Mr. Drexler, but none from Ms. Lyons although Mr. Sikhounmuong will report directly to her, as he did at Madewell. That suggests either she is being protected, or she is being hidden, or they still have faith in her, or she is on the line. It could be any of the above.

But Madewell and J. Crew are not the same thing (if they were, you wouldn’t need both of them), and I always find this kind of assumed transference puzzling. Just because a designer is great at articulating and cutting into the cloth of the values and identity of one brand does not automatically mean he will be able to do the same at another, much larger, brand, with different exigencies.

The designers Mrs. Obama chose, while meaningful names on the London Fashion Week schedule, are all trying to break through internationally. Her stamp of approval is not an insignificant asset.

Come September, and fashion week, we’ll see what difference it makes.

So why the change? Maybe it has to do with term one versus term two for President Obama, and with solidifying international relations, the better to work on legacy questions. Maybe it’s about strategically using all the attention paid to what she wears to the benefit of brands throughout the world. Maybe it’s just good diplomacy.

That’s not to say Mr. Sikhounmuong can’t fix J. Crew. And perhaps his appointment means that his skill set — imbuing American classics with a subversive, and very subtle, edge of cool — will determine the future look of the big brand, which may move away from some of the sequined, print-heavy, fun-in-the-city-sun pieces that have been the norm of late, and concentrate more on the basics. And J. Crew has never been known for its handbags. Maybe accessories will be a new focus.

J. Crew just isn’t selling. With sales down for another consecutive quarter, doomsayers are circling. Interestingly, however, while normally the first solution when product has not been resonating is, “Fire the creative director!” (see Gucci, which also fired its chief executive), that has not been this brand’s solution. Instead, it has replaced the design second-in-command.

And though matching clothes to country is in line with her appearance in Tadashi Shoji at a state dinner at the White House for Japan’s prime minister in April, the all-British-brands-all-the-time approach is a marked departure from her approach during a visit to London in 2011.

And in Christopher Kane, for a meeting with Prime Minister David Cameron and his wife, Samantha.

That’s a lot of very specific fashion to pack into a relatively short visit and a clear show of support, especially because these brands are not widely stocked in the United States. Mary Katrantzou is sold in 10 stores on the entire East Coast, for example. Christopher Kane has five.

It will be interesting to see how this plays out on the next leg of her trip, in Italy.

Indeed, in all the gleeful picking over of J. Crew’s problems — and fashion loves nothing more than seeing a runaway success, which J. Crew was, fall on its face — Ms. Lyons, who has been promoted as the face of the brand and who has become a quasi design celebrity in her own right, has been notably absent.

In Mary Katrantzou, at the Mulberry School for Girls in east London.

Since landing on Monday, Mrs. Obama has worn clothes from three different London-based designers: Preen by Thornton Bregazzi when disembarking the plane; Mary Katrantzou while visiting a school and having tea with Prince Harry; and Christopher Kane while meeting Prime Minister David Cameron and his wife, Samantha.

You can understand why Mr. Drexler and Ms. Lyons wanted to move him. It’s the usual fashion magical thinking: It worked over there; it can work over here!