 In 1607, the castle was purchased by Thomas Liddell, a wealthy Newcastle-upon-Tyne merchant.Liddell and his family would hold onto the estate for the following 300 years, much of their fortune would come from coal mining on the land, beginning in the early 17th century.In 1724 Sir Henry Liddell built a substantial mansion within the curtilage of the castle, but this was demolished in 1808 by Sir Thomas Liddell, and replaced by a grand house designed in the Gothic Revival style by architect John Nash.