Question: Who is the maternal grandfather of Peter Llewelyn Davies?
Sentence (from "Sylvia Llewelyn Davies"): She was the daughter of cartoonist and writer George du Maurier and his wife Emma Wightwick, the elder sister to actor Gerald du Maurier, the aunt of novelists Angela and Daphne du Maurier and a great-granddaughter of Mary Anne Clarke, royal mistress of Prince Frederick, Duke of York and Albany.
Relevant evidence: Yes