The hotel gained prominence during the 1902–1952 management of the self-made hotelier and socialite Rosa Lewis, who was also known as the "Queen of Cooks" and "The Duchess of Jermyn Street"; damaged in the London Blitz, it was torn down in 1962.

By 1904, though, the hotel was not going very well: debts spiralled out of control, Excelsior was having a drinking problem and, therefore, Rosa decided to throw them out and divorce her husband.

In 1944, Rosa Lewis became ill and had to go to a nursing home, leaving her friend Edith Jeffrey in charge of the hotel, which was already showing some signs of decline.

For another ten years, Edith Jeffrey continued to run the hotel, then in a state of decline, until her own death.

The new Cavendish Hotel, completely re-built and bearing no relation at all to its magnificent predecessor, opened its doors in July 1966.

The 1970s BBC series The Duchess of Duke Street was a fictional adaptation with elements taken from the hotel, Rosa Lewis and her husband's story.