Complex sentence: Lennox was styled Earl of March, his father's principal subsidiary title, from birth, his early education was had at Westminster School and he succeeded his father as Duke of Richmond and Lennox in 1750.
Split into simpler sentences: Lennox was styled Earl of March, his father's principal subsidiary title, from birth. He received his early education at Westminster School and succeeded his father as Duke of Richmond and Lennox in 1750.