Complex sentence: Neville's father was a great-great-grandson of Ralph Neville, 1st Earl of Westmorland and Joan Beaufort, Countess of Westmoreland, the daughter of John of Gaunt, 1st Duke of Lancaster by Katherine Swynford.
Split into simpler sentences: Neville's father was the great-great-grandson of Ralph Neville, 1st Earl of Westmorland and Joan Beaufort, Countess of Westmoreland. Joan was daughter of John of Gaunt, 1st Duke of Lancaster and Katherine Swynford.