The current issue of the New Criterion carries a review of Renishaw Hall: The Story of the Sitwells by Desmond Seward. The review by Brooke Allen notes the importance of the Sitwells and their house to Evelyn Waugh:
According to Evelyn Waugh, [the Sitwells] “radiated an aura of high spirits, elegance, impudence, unpredictability, above all of sheer enjoyment. They declared war on dullness.”… Seward, a close friend of Sir Reresby and his wife Penelope, is hardly the first to fall besottedly in love with Renishaw and its famous gardens. The artist Rex Whistler considered it “the most exciting house in England.” Evelyn Waugh, who visited the Hall often as Osbert’s guest, grew to care for it even more than he did for Madresfield Court, the model for his fictional Brideshead.
The bracketed reference is to the siblings Edith, Osbert and Sacheverell Sitwell who occupied the house during Waugh’s lifetime. The quote is from a profile Waugh wrote on Osbert for the New York Times Magazine (30 November 1952). It is reprinted in Essays, Articles and Reviews, p. 423.