Complex sentence: The son and heir of John Fitzalan, Lord of Oswestry and Clun, in Shropshire, and Isabel, daughter of William d'Aubigny, 3rd Earl of Arundel by his wife, Mabel of Chester.
Split into simpler sentences: The son and heir of John Fitzalan, Lord of Oswestry and Clun, from Shropshire. His mother, Isabel, was daughter of William d'Aubigny, 3rd Earl of Arundel by his wife, Mabel of Chester.