In the 1770s Valentine Morris's gambling, business and political dealings bankrupted him, and he was forced to leave Piercefield for the West Indies. In 1785, Piercefield was sold again, for £26,200, to George Smith, a Durham banker, father of the linguist Elizabeth. Smith continued to open the walks, but straightened some of them. He also commissioned a young architect, John Soane to design a new mansion in the neo-classical style, which would incorporate Morris's house. Work began in 1792, and the new three-storey stone building had reached roof level when Smith found himself in financial difficulties. He sold Piercefield in 1794 to Colonel Mark Wood, Member of Parliament for Newark-on-Trent, who continued and modified the work with architect Joseph Bonomi, incorporating a Doric portico and wings, and commissioning the long stone wall which runs along the edge of the estate. Wood was also the owner of Llanthony Priory. In 1802, Wood in turn sold the house and estate to the mixed race planter Nathaniel Wells, for £90,000 cash. Wells was born in St Kitts, the son of William Wells, a sugar merchant and planter originally from Cardiff, and Juggy, one of his house slaves. With his inherited fortune, Wells continued to add to the Piercefield estate until it reached almost 3,000 acres (12 km²). In 1818 he became Britain's only known black sheriff when he was appointed Sheriff of Monmouthshire.