Complex sentence: He was of Scottish parentage where he also spent part of his upbringing but was born in Portsmouth, England, he served his long parliamentary career for a seat in the county of London and lived much of his life in England.
Split into simpler sentences: He was of Scottish parentage where he also spent part of his upbringing but was born in Portsmouth, England. He served his long parliamentary career representing a constituency in the County of London and lived much of his life in England.