Question: Who is the maternal grandmother of Henry Percy, 1St Earl Of Northumberland?
Sentence (from "Henry Percy, 1st Earl of Northumberland"): Henry Percy, 1st Earl of Northumberland, 4th Baron Percy, titular King of Mann, KG, Lord Marshal (10 November 134120 February 1408) was the son of Henry de Percy, 3rd Baron Percy, and a descendant of Henry III of England.
Relevant evidence: No