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 Vane-Tempest-Stewart family, Marquesses of Londonderry. The house and its contents reflect the history of the Vane-Tempest-Stewart family, who played a leading role in British and Irish social and political life.
Mount Stewart was formed by the Stewart family (later Vane-Tempest-Stewart), holders of the title Marquess of Londonderry since 1816. The family bought the estate in 1744 with money acquired by Alexander Stewart (1699?1781). This new wealth came from the sales of materials like linen. At the time, the house was known as Mount Pleasant.
Alexander Stewart’s son, Robert Stewart, became the first Marquess of Londonderry. In about 1800 he added a temporary wing to the west. He died in 1821 leaving the house to his son, also Robert, better known as Viscount Castlereagh, one of Britain’s most famous Foreign Secretaries. Castlereagh lived in Mount Stewart during his childhood until he went to University in Cambridge.
Lord Castlereagh inherited his father’s title only a year before his own death. The next owner of the house was his half-brother, Charles, 3rd Marquess of Londonderry (1778?1854). He married twice but it was his later marriage which increased the family’s finances greatly. His second wife was Lady Frances Anne Vane-Tempest. She was the greatest heiress of her time. This huge new wealth prompted the refurbishment and enlargement of the newly renamed Mount Stewart.