"and walked in the twilight to the Ritz grill"
The Ritz Hotel, London
Creative Commons Attribution Share AlikeThe Ritz Hotel, London - Credit: Dickbauch, Wikimedia Commons

The Ritz is a prestigious London hotel which opened in 1906. It is situated on Piccadilly, overlooking Green Park.

The hotel's eatery is now known as The Ritz Restaurant, but presumably at the time of Brideshead Revisited it was known as The Ritz Grill.

In The Acceptance World (the third novel in Anthony Powell's twelve-novel sequence, A Dance to the Music of Time), set in the 1930s, the narrator accepts an invitation to gnaw a cutlet at the Grill.