Complex sentence: Her paternal grandparents were William de Braose, 3rd Lord Bramber and Bertha of Hereford, and her maternal grandparents were Bernard de St. Valery and Matilda.
Split into simpler sentences: Her paternal grandparents were William de Braose, 3rd Lord Bramber and Bertha of Hereford. Her maternal grandparents were Bernard de St. Valery and Matilda.