Mary Constance Wyndham Charteris (Countess of Wemys) was the oldest daughter of Percy Wyndham (1835-1911) and Madeline Caroline Frances Eden Campbell (Mrs P. Wyndham) (1835-1920). She married Hugo Richard Charteris, 11th Earl of Wemys (1857-1937).
She was a society hostess, and member of the 'Souls'. She inherited Nocturne: Grey and Gold - Westminster Bridge y145.
UK death and census records, Ancestry.com.
Who's Who, 1905; Debrett's Peerage, Baronetage and Knightage, London, 1896.