Princess Kate's Sister-in-Law Delivers a Dose of French Fashion to Royal Carol Concert in a Cool-Girl Sézane Suit

Alizée Thevenet departed from the family's blue-and-green theme in a '70s-inspired outfit.

James Middleton wearing a blue coat next to Alizee Thevenet in a plaid suit
(Image credit: Getty Images)

Princess Kate's brother, James Middleton, and his wife, Alizée Thevenet, rarely make public appearances with the Royal Family, but there's one event you can guarantee they're not going to miss each year. The couple, joined by parents Carole and Michael Middleton, made their annual appearance at Princess Kate's Together at Christmas concert on Friday, December 5.

Carole coordinated with the entire Wales family—who wore shades of blue and green to the concert—in a black watch tartan coat, while James looked dapper in a navy wool coat, skinny trousers and whimsical red dog socks. But French-born Alizée skipped the blues and greens in favor of a very Parisian outfit at Westminster Abbey.

Thevenet arrived at the concert in an oversized beige checked coat by it-girl label Sézane, pairing it with the brand's matching Ciara trousers. The slightly flared, cropped pants combined with the outfit's camel, black and brown pattern gave her outfit a very '70s vibe, and she paired it with a white sweater with a ruffled collar and a pair of tan suede booties.

James Middleton and Alizee Thevenet at the Together at Christmas 2025 concert

Alizée Thevenet and James Middleton are pictured at the 2025 Together at Christmas concert.

(Image credit: Getty Images)

James Middleton and Alizee Thevenet arriving at the Together at Christmas concert

Alizée Thevenet and James Middleton are pictured at the 2025 Together at Christmas concert.

(Image credit: Getty Images)

Alizée added another French-girl touch to her outfit, carrying a burgundy Longchamp bag from the Parisian brand's new collection. She removed the leather design's crossbody strap and carried it by its handles as she arrived at the concert, which is held at Westminster Abbey each December.

James and Alizée married in 2021 and welcomed their son, Inigo, in 2023. The couple live in Berkshire near the Middletons and are famous dog lovers, with James crediting his late dog, Ella, for saving his life during a period of deep depression and suicidal ideation.

Carole Middleton and Michael Middleton walking with an umbrella outside Westminster Abbey at the Together at Christmas concert

Carole and Michael Middleton are seen arriving at the 2025 Together at Christmas concert.

(Image credit: Getty Images)

As for James's big sister, Kate, she re-wore a forest green Catherine Walker coat and a Troy London fur collar for the 2025 Together at Christmas concert, adding a Miu Miu tartan skirt underneath.

Prince George, Princess Charlotte and Prince Louis also attended the festive event, with Charlotte, 10, trading her favorite Trotters coat for a cropped navy jacket with a white pilgrim collar and a matching navy dress. Meanwhile, George, 12, and Louis, 7, matched with dad Prince William in blue suits and blue-and-green ties.

Kristin Contino
Senior Royal and Celebrity Editor

Kristin Contino is Marie Claire's Senior Royal and Celebrity editor. She's been covering royalty since 2018—including major moments such as the Platinum Jubilee, Queen Elizabeth II’s death and King Charles III's coronation—and places a particular focus on the British Royal Family's style and what it means.

Prior to working at Marie Claire, she wrote about celebrity and royal fashion at Page Six Style and covered royalty from around the world as chief reporter at Royal Central. Kristin has provided expert commentary for outlets including the BBC, Sky News, US Weekly, the Today Show and many others.

Kristin is also the published author of two novels, “The Legacy of Us” and “A House Full of Windsor.” She's passionate about travel, history, horses, and learning everything she can about her favorite city in the world, London.