Page 417. " Beatrice’s London abode was a delightful Victorian terraced townhouse on Lancaster Gate in the fashionable Bayswater district. "

London townhouses
Creative Commons Attribution Share AlikeLondon townhouses - Credit: Stephen Richards
This is what Lady Beatrice’s London townhouse might have looked like.

Page 418. " they went for tea in the sumptuous Palm Court at the Ritz "

Take a brief tour of the Ritz hotel in this video.

Page 421. " Blackthorn is Sid’s family estate in Berkshire "

Lady Sidonie's Elizabethan estate might have resembled this one - Longleat House.

Elizabethan Longleat House
Public DomainElizabethan Longleat House
Page 421. " She was determined to come to visit us in Oxford, but girls weren’t allowed in our rooms. So she borrowed her younger brother’s clothes and identity, and came to stay with Quentin for an entire weekend "
Magdalen College Oxford
Creative Commons Attribution Share AlikeMagdalen College Oxford - Credit: Ozeye

These are the Magdalen College residences where she would have stayed with her brother. Edward, Prince of Wales, was at Magdalen at the same time as the characters in the novel, who consequently befriended him.