Little Cressida Ellis sat in a circle of well-groomed children. A mile to the west of the Palace, on the southern edge of Belgravia, the school day was finishing at the Montgomery Nursery School.

Cressida and her friends wore a wide selection of the Ralph Lauren children’s range, with a smattering of Gucci and Stella McCartney.

“- bā, jiǔ, shí.” Cressida said, along with all the other children.

“Well done, everyone” said their teacher, Karen. “Now,...