Question: This mansion in St James's, London is the property of a nobleman who was the younger brother of who?
Sentence (from "Charles Spencer, 9th Earl Spencer"): Charles Edward Maurice Spencer, 9th Earl Spencer, (born 20 May 1964), styled Viscount Althorp between 1975 and 1992, is a British nobleman, peer, author, print journalist, and broadcaster, and was the younger brother of Diana, Princess of Wales.
Relevant evidence: Yes