Complex sentence: The date of the birth of his son Robert is not known, nor are there records of his career until we find him, in 1324, a member of the parliament of Westminster, and afterwards occupying positions of great importance and trust.
Split into simpler sentences: The date of the birth of his son Robert is not known, nor are there records of his early career. Sir Robert is first mentioned in 1324, as a member of the parliament of Westminster, and afterwards occupying positions of great importance and trust.