The Duchess of Cambridge wore a cosy-looking red jumper. Underneath she wore the Sézane Margeurite Blouse.
Operating out of Paris, the brand releases a seasonal collection four times a year.
Once a month there is a smaller collection and every Wednesday details of new collections and restocking.
Kate has a number of other items from the brand, including the Artemis belt.
The Duchess also owns Sezane’s Tulio jumper in merino wool.
Personal stylist and fashion expert Samantha Harman spoke exclusively to Express.co.uk about Kate’s sustainable wardrobe, giving her analysis on how “thrifty” Kate is in reality, and what her fashion choices mean.
Samantha emphasises that “the royals are the best example of why what you wear matters”.
She said: “They use clothing to build and sustain relationships, convey messages and help causes they feel passionately about.
“When you’re on a world stage, how you dress is always going to be scrutinised,” Samantha added.