Complex sentence: In 1770 it was inherited by George Cholmondeley, the 4th Earl of Cholmondeley, who decided to replace it with a new building and demolished most of the Old Hall.
Split into simpler sentences: In 1770 it was inherited by George Cholmondeley, who was then the 4th Earl of Cholmondeley. He decided to replace it with a new building, and demolished most of the Old Hall.