Complex sentence: Baldwin suggests that the "Richard Plantagenet" who died in December 1550 in Eastwell, Kent, was the lost prince; Richard of Eastwell himself claimed to be a son of King Richard III of England.
Split into simpler sentences: Baldwin suggests that the "Richard Plantagenet" who died in December 1550 in Eastwell, Kent, was the lost prince. Richard himself claimed to be a son of King Richard III of England.