Mount Stewart is a 19th-century house and garden in County Down, Northern Ireland, owned by the National Trust. Situated on the east shore of Strangford Lough, a few miles outside the town of Newtownards and near Greyabbey, it was the Irish seat of the Stewart family, Marquesses of Londonderry. Prominently associated with the 2nd Marquess, Robert Stewart, Viscount Castlereagh, Britain's Foreign Secretary at the Congress of Vienna and with the 7th Marquess, Charles Vane-Tempest-Stewart, the former Air Minister who at Mount Stewart attempted private diplomacy with Hitler's Germany, the house and its contents reflect the history of the family's leading role in social and political life in Britain and Ireland. History County seat of the Stewarts, Lords Londonderry and Castlereagh The original property, Mount Pleasant, was purchased with neighbouring estates in 1744 by Alexander Stewart (1699–1781). Exceptionally for an aspiring member of the landed Ascendancy, the Stewarts did not conform to the established (Anglican) church. They were Presbyterians, farmers and linen merchants whose fortunes had been transformed by Alexander's marriage to the sister and heiress of Robert Cowan, the East India Company Governor of Bombay. As fellow Presbyterians, the Stewarts appeared to the county's enfranchised forty-shilling freeholders as "friends of reform", and on that basis Mount Stewart rivalled Hillsborough Castle, seat of the Earls (later Marquesses) of Downshire, for control of the county's two parliamentary seats. In the increasingly troubled 1790s, Mount Stewart quietly converted to Anglicanism and stilled the contest, agreeing with Hillsborough that each should return a member to the parliament in Dublin unopposed. Titles and office followed. In 1795 Alexander's son, Robert Stewart (1739–1821) was elevated to Earl of Londonderry (Marquess in 1816), and in 1797 his son Robert Stewart, Viscount Castlereagh (1769–1822), was appointed Chief Secretary for Ireland by the Lord Lieutenant, Londonderry's brother-in-law, John Pratt, Earl Camden. After helping, in the wake of the 1798 rebellion, to push the Act of Union through the Irish Parliament, bringing Ireland under the Crown at Westminster, Castlereagh went on to serve the new United Kingdom as Secretary for War and Foreign Secretary, building the coalitions that defeated Napoleon. In 1787, writing to her brother William Drennan (a disappointed supporter of the Stewarts' electoral ambitions, later to be targeted by Castlereagh as a United Irishman), Martha McTier described visiting Mount Stewart, and meeting "with no one thing worth notice, unless great wall pounds are so – much expense, no