of Northumberland (1644–1670), who brought him immense estates, including Alnwick Castle, Northumberland; Petworth House, Sussex; Leconfield Castle, Yorkshire; Cockermouth Castle, Cumberland; Egremont Castle, Cumberland; Syon House, Middlesex, and Northumberland House in London. It had been agreed in the marriage settlement, although both parties to the marriage were minors, and thus legally incapable of being bound by a contract, that: "... for the preservation of the noble family and name of the Percys, he the said duke and all and every the issue of his body on her the said duchess begotten, should forever take upon him and them and be called and named only by the name and surname of Percy". However, on attaining her majority of 21 the duchess under her hand and seal dated 30 January 1687 consented to waive and dispense with the agreement. The intention stated in the marriage contract was however fulfilled in 1749 by their granddaughter Lady Elizabeth Seymour and her husband the former Sir Hugh Smithson, 4th Baronet (who by special remainder had inherited in 1749 his father-in-law's title Earl of Northumberland) when in 1749 they obtained a private Act of Parliament entitled: "An Act to enable Hugh Earl of Northumberland and Elizabeth Countess of Northumberland and Barones Percy, his Wife, and their Children, Progeny and Issue, to take and use the Name of Percy, and bear and quarter the Arms of the Percies Earls of Northumberland". The reason for the name-change was stated in the preamble to the Act as follows: "And as Algernon, late Duke of Somerset, did in his lifetime express his desire that the name of Percy should be used by and be the surname and family name of the Earls of Northumberland ... Sir Hugh Smithson now Earl of Northumberland and Lady Elizabeth his wife, Countess of Northumberland and Baroness Percy, as well out of their great regard to, and in compliance with the desire of, the said late duke, as for preserving the noble and ancient family and name of Percy and the coats of arms borne and quartered by the Percys Earls of Northumberland should be ... confirmed ... upon them ... by authority of Parliament". Rebuilds Petworth House Between 1688 and 1696 the Duke rebuilt Petworth House on a palatial scale. A painting made in about 1700 of his new house was identified by the art historian Sir Anthony Blunt in the collection of the