Question: When did Joan Beaufort, Countess Of Westmorland's father die?
Sentence (from "Joan Beaufort, Countess of Westmorland"): Joan Beaufort (– 13 November 1440), was the youngest of the four legitimised children and only daughter of John of Gaunt, 1st Duke of Lancaster (third surviving son of King Edward III), by his mistress, later wife, Katherine Swynford.
Relevant evidence: Yes