Davidson, Thomas, 1722-1781.

Hugh Smithson, fourth baronet of Stanwick in Yorkshire, married the heiress to the Percy title and estates in 1740 over the objections of her family. In 1750, shortly after her succession as Baroness Percy suo jure, Hugh Smithson took the surname Percy by Act of Parliament and was seated in the House of Lords as Earl of Northumberland. He was created Duke in 1766 with the support of William Pitt.

Northumberland was active in politics for over thirty years. He instituted many agricultural improvements on the Percy estates, reclaiming land and rebuilding laborers' cottages, and developed highly profitable coal mines. He renovated Alnwick Castle, hiring Robert Adam as architect and designer, was elected a Fellow of the Royal Society, and was a founding Trustee of the British Museum.

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