Complex sentence: Having become a friend of Oliver Cromwell, he was a member of the Council of State from 1649 to 1653, and was its president in 1652 and 1653; he also served as comptroller of the receipts of the Exchequer.
Split into simpler sentences: Having become a friend of Oliver Cromwell, he was a member of the Council of State from 1649 to 1653, and was its president in 1652 and 1653. He also served as comptroller of the receipts of the Exchequer.