"The old Duchess d'Uzès use to tell me"

Probably either Anne de Rochechouart de Mortemart (1840 – 1878) or Marie Thérèse d'Albert de Luynes (1871 – 1943), although Elliott seems hardly old enough to have met the former and the latter seems hardly old enough to merit Elliott's tone.

Uzès is in the Languedoc, in southern France. The title of duke of Uzès is the premier title in the peerage of France.