Complex sentence: Carileph and successive bishops, had nearly all the powers within their County Palatinate that the king had in the rest of England, but although often called "Prince Bishops" it was not a title used by any of the office holders.
Split into simpler sentences: Carileph and successive bishops had nearly all the powers within their County Palatinate that the king had in the rest of England. Although they were often called "Prince Bishops" this title was not actually used by any of the office holders.