Complex sentence: Calvert was born at Glossop Hall in Derbyshire, on 23 September 1785, the eldest son of another Charles Calvert, agent of the Duke of Norfolk's estate and an amateur painter (see below).
Split into simpler sentences: Calvert was born at Glossop Hall in Derbyshire, on 23 September 1785. He was the eldest son of Charles Calvert, agent of the Duke of Norfolk's estate and an amateur painter (see below).