The title Duke of Northumberland was created in 1551 for John Dudley. He supported the claim of his daughter-in-law, Lady Jane Grey, to the English throne, but when she was deposed by Queen Mary, Dudley was convicted of high treason and executed. George Fitzroy was awarded the title in 1674, but it became extinct as Fitzroy left no heirs. The title was created for the third time in 1766, and it has been in the Percy family ever since. The seat of the Dukes of Northumberland is Alnwick Castle, in Alnwick, Northumberland; their London residence is Syon House in Brentford.
The subsidiary titles of the Duke of Northumberland are: Earl of Northumberland (created 1749), Earl Percy (1766), Earl of Beverley (1790), Baron Warkworth (1749) and Baron Lovaine of Alnwick (1784). All titles are in the Peerage of Great Britain. The courtesy title of the eldest son and heir to the Duke is Earl Percy.
