History of Mount Stewart

Expert curated

The Black and White Stone Hall at Mount Stewart, where armour is displayed along the walls and a marble sculpture of Helen of Troy can be seen — The Black and White Stone Hall at Mount Stewart, County Down | © National Trust Images/Andreas von Einsiedel

Mount Stewart, County Down, is one of Northern Ireland’s most significant historic estates. Home to the influential Stewart family for over two centuries, its story is tied to the rise of the Anglo-Irish aristocracy, major political shifts in Britain and Ireland, and global connections through empire, diplomacy and war. From the ambitions of Alexander Stewart to the legacy of Viscount Castlereagh and the vision of Edith, Lady Londonderry, Mount Stewart reflects evolving ideals of power, taste, and identity from the eighteenth century to today.

Early origins and the Stewart family

The land at Mount Stewart, situated on the Ards Peninsula, was purchased in 1744 by Alexander Stewart (1700–81), a wealthy linen merchant from Donegal. The acquisition was funded by the fortune of his wife, Mary Cowan (1713–88), which she had inherited from her brother, Sir Robert Cowan (died 1737), an East India Company merchant and Governor of Bombay. Their investment reflected a wider trend of land consolidation by Protestant families following the Plantation of Ulster – the redistribution of land to English and Scottish settlers during the early 17th century.

What began as a modest house overlooking Strangford Lough was expanded in the 1780s by Alexander and Mary’s son Robert Stewart (1739–1821), 1st Marquess of Londonderry. He commissioned a walled garden, new farm buildings by James Wyatt, and the Temple of the Winds. Designed by James ‘Athenian’ Stuart, this latter was a carefully proportioned neoclassical pavilion, inspired by an ancient monument in Athens.

Viscount Castlereagh: power and legacy

Robert Stewart (1769–1822), better known as Viscount Castlereagh and later the 2nd Marquess of Londonderry, entered politics in the 1790s. He became Chief Secretary for Ireland during the 1798 Rebellion against the British Crown and played a key role in the passage of the Acts of Union (1800) which joined the British and Irish parliaments. These actions earned him hostility in Ireland, though he was widely respected in England and abroad for his diplomatic prowess.

From 1802 to 1822, Castlereagh held high office in successive British governments, most notably as Secretary of State for Foreign Affairs. At the Congress of Vienna (1814–15) he helped redraw the map of Europe following the final defeat of Napoleon Bonaparte. He also supported the abolition of slavery as a moral imperative. Among the collections at Mount Stewart is a desk and set of chairs used at the Congress, as well as Castlereagh’s silver inkstand.

Oil Painting on canvas. Robert Stewart, Viscount Castlereagh, 2nd Marquess of Londonderry (1769-1822), British (English) School, after Sir Thomas Lawrence, PRA (Bristol 1769, London 1830), 20th century. — Oil Painting on canvas. Robert Stewart, Viscount Castlereagh, 2nd Marquess of Londonderry (1769-1822), Mount Stewart, County Down | © National Trust Images

Expansion and influence

After Castlereagh’s death in 1822, Mount Stewart passed to his half-brother, Charles Stewart (1778–1854), 3rd Marquess of Londonderry. A military officer and diplomat, Charles served as British Ambassador to Vienna and Berlin. His 1819 marriage to Frances Anne Vane-Tempest (1800–65), heiress to vast coal wealth in County Durham, significantly increased the family's fortune.

This income funded extensive remodelling of the house in the 1830s and further development of the estate. The family also rebuilt their English residences, Seaham Hall and Wynyard Park in County Durham, and Londonderry House, London, reflecting their growing influence across the United Kingdom.

Mount Stewart and politics in Ireland

Mount Stewart remained a political stronghold into the twentieth century. Charles Vane-Tempest-Stewart, 6th Marquess (1852–1915), served as Lord Lieutenant (or Viceroy) of Ireland during the 1880s and opposed Irish Home Rule. He and his wife were among the earliest signatories of the Ulster Covenant in 1912, pledging resistance to Irish self-government.

Their son, also called Charles, the 7th Marquess (1878–1949), served in the First World War (1914–18) and later held office in the British government, including as Secretary of State for Air. He and his wife Edith (1878–1959) were key figures in the new Northern Ireland administration following partition – the separation from the rest of newly independent Ireland – in 1921. Edith also founded the Women’s Legion during the war and played a transformative role in the development of Mount Stewart in the years that followed.

Lady Londonderry’s vision

From the 1920s, Edith redesigned the house’s interiors, blending inherited heirlooms with bold decorative schemes. Her work extended outdoors, where she designed and created the celebrated gardens. Blending Italianate and Spanish influences and references to Scottish and Irish folklore, these formal and informal spaces are adapted to the mild microclimate of Strangford Lough and remain a living testament to Edith’s imagination and skill.

View of the house from the Spanish garden at Mount Stewart, County Down | © National Trust Images/James Dobson

Given to the National Trust

Anticipating the challenges of maintaining the gardens, Edith began negotiations to transfer them to the National Trust in the 1950s. The first transfer of land took place in 1955. Following her death in 1959, her daughter, Lady Mairi Bury (1921–2009), inherited the house and continued the family’s stewardship.

In 1977, Lady Mairi gave the house and selected contents to the National Trust, along with the Temple of the Winds and additional land. She remained in residence for the rest of her life, actively involved in how the house was presented. As part of the settlement of her estate, the remainder of the collection was accepted by the Government in lieu of inheritance tax and allocated to Mount Stewart.

Following the death of Alexander Vane-Tempest-Stewart, 9th Marquess of Londonderry (1937–2012), an additional group of works of art and furnishings was given on loan to Mount Stewart by his estate. Between 2012 and 2015, the National Trust carried out an ambitious restoration project at Mount Stewart, involving major structural repairs, conservation of historic interiors, reinstallation of textiles and reinterpretation of key rooms.

Collections

Mount Stewart’s collections offer a vivid picture of aristocratic life, public service, and personal ambition. The house contains a rich array of furniture, paintings, ceramics, silverware, archival material and political and military memorabilia acquired over generations. Among the highlights are portraits by leading artists such as Pompeo Batoni, George Stubbs, Sir Thomas Lawrence, Philip de László and Sir John Lavery, which reflect the family’s stature in both British and European society.

Various medals and orders on display at Mount Stewart, County Down | © National Trust Images / Andreas von Einsiedel

Mount Stewart today

Mount Stewart continues to reveal new insights into its architecture, collections, and multifaceted histories, connecting the estate to broader narratives of British and Irish heritage. It tells the story of a family whose influence reached from rural County Down to the heart of British politics and European diplomacy. Today, it remains a powerful window into the intertwined histories of Ireland, Britain and the wider world.