Complex sentence: He was Bishop of Llandaff from 1819 to 1826, from whence he translated to Durham; prior to this, he had been rector of the church of St. Mary-le-Bow in London as well as Dean of St Paul's between 1820 and 1826.
Split into simpler sentences: He was Bishop of Llandaff from 1819 to 1826, from whence he transferred to Durham. Prior to this, he had been rector of the church of St. Mary-le-Bow in London as well as Dean of St Paul's between 1820 and 1826.