James Smithson (left), whose bequest founded the Smithsonian Institution, was the "illegitimate" son of Langdale Smithson of Langdale, Yorkshire — and the half-brother of Hugh Percy (right), the first Duke of Northumberland.
Percy (1714–1786) was an English peer, landowner, and art patron. He was actually born Hugh Smithson, a "legitimate" son of Langdale Smithson. After Hugh married Lady Elizabeth Seymour, the Baroness Percy, he changed his name to Percy.
The Percy family has lived in Alnwich Castle for centuries.