Skip to content

History of Mount Stewart

Lady Londonderry's Sitting Room at Mount Stewart, with couches, armchairs and side tables, along with bookcases and family belongings in the background
Lady Londonderry's Sitting Room at Mount Stewart | © National Trust Images / Elaine Hill Photography

Mount Stewart is steeped in history. The people who lived and worked here are connected to many significant events in European history, from the Congress of Vienna to the First World War. Discover the events and people that underpin Mount Stewart’s history.

Building Mount Stewart

The Stewart family came from Scotland to Donegal as part of the Jacobean Plantation of Ulster. Alexander Stewart and his wife, Mary Cowan, bought a large area of land in County Down in 1744, part of which became Mount Stewart demesne. Mary had inherited a fortune from her brother, Robert Cowan, who was in the East India Company, and was Governor of Bombay.

A modest house on the shore of Strangford Lough was extended in the 1780s into a long low two-storey house by Alexander’s son, Robert. Robert also built a walled garden and farm buildings further inland, and commissioned James ‘Athenian’ Stuart to design the Temple of the Winds, one of the finest small neo-classical buildings in Ireland.

Through his political connections and marriage, Robert rose through the political ranks, becoming Earl and subsequently Marquess of Londonderry.

It was Robert’s son, best known as Viscount Castlereagh, who chose the architect George Dance to design a new wing for Mount Stewart which included a series of fine reception rooms. The west wing was built around 1804–6.

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.
Viscount Castlereagh | © National Trust Images

Robert Stewart, Viscount Castlereagh, 2nd Marquess of Londonderry

Oil Painting on canvas of Robert Stewart, Viscount Castlereagh, 2nd Marquess of Londonderry (1769-1822), Mount Stewart, County Down.

Viscount Castlereagh

Castlereagh is best known in Ireland for his involvement in the repression of the 1798 Rebellion and as one of the architects of the Anglo-Irish Union of 1800, for which he was vilified by many. He was however regarded as a consummate statesman and astute negotiator.

From 1802 to 1822 he was based in London as Secretary of State for War and Foreign Secretary during the wars with America and France under Napoleon. He was one of the chief negotiators at the Congress of Vienna (1814-15) and his greatest legacy was steering the Congress towards a more equitable balance of power.

The Congress was the first multinational European congress; many issues were discussed including the abolition of slavery. Castlereagh became a staunch supporter of abolition, as the trade was 'repugnant to the principles of humanity and universal morality.

The Peterloo Massacre of 1819 earned him more criticism, for although he was not personally responsible and was appalled by the outcome, as Home Secretary he had to justify the yeomanry’s actions. In 1822 he suffered a breakdown and took his own life, just a year after becoming the 2nd marquess of Londonderry.

A family walking across the garden lawn surrounded by flower beds and hedges at Mount Stewart, with a view of the house in the background
Family exploring the garden in spring at Mount Stewart | © National Trust Images / John Millar

Castlereagh: Life & Legacy Exhibition

A new exhibition to mark the 200th anniversary of the death of Viscount Castlereagh (1769-1822) opened at Mount Stewart in August 2022. The exhibition provides an introduction to the life of this complex man who lived in extraordinary times and believed he was striving for the greater good. Explore his life and legacy through his family, politics and role as a statesman.

A silver inkstand, which served as a constant companion to Viscount Castlereagh and was used to write letters which shaped post-Napoleonic Europe, will be displayed publicly for the first time at his former home, as part of the exhibition. The inkstand is one of the most personal pieces associated with Castlereagh. It would have been used in the composition of letters of vital importance to sovereigns, statesmen and generals including Tsar Alexander I of Russia, the Duke of Wellington and even Napoleon’s marshal Ney. It is likely to have been present when Castlereagh interviewed Nelson before the Admiral’s departure for the Battle of Trafalgar and used to compose letters to the Duke of Wellington ahead of the Battle of Waterloo.

Who was Viscount Castlereagh?

Robert Stewart, Viscount Castlereagh and later 2nd Marquess of Londonderry, was born in Dublin in 1769 and spent his youth at the Stewart family home at Mount Stewart, inheriting the estate himself in 1821. He embarked on a political career, representing County Down in the House of Commons in Dublin, before being elected to the House of Commons in London in 1794. This same year he married Lady Amelia Hobart who he remained close to for the rest of his life.

Four years later he was appointed Chief Secretary of Ireland, in effect the Prime Minister, and the first Irish man to ever hold this position. In post, he was responsible for suppressing the civil disobedience during the 1798 Rebellion, while also commanding the local Militia and defending Ireland against the attempted French invasion. The same role of Chief Secretary saw him steer the Acts of Union through both Dublin and London parliaments, creating the United Kingdom of Great Britain and Ireland.

His political career continued for the rest of his life, as Secretary of State for War and the Colonies, Leader of the House of Commons and Foreign Secretary. As British Foreign Secretary he brought together a coalition of six European countries that defeated Napoleon and saw him leading the Congress of Vienna that sought to establish long-term peace after 23 years of European war against France.

A curator wearing gloves examining a silver inkstand on a pillow
The silver inkstand used by Viscount Castlereagh to write historic correspondence | © National Trust Images/James Dobson

Charles Stewart and the extension of Mount Stewart

Castlereagh’s half-brother, Charles Stewart fought in the Peninsula War under Wellington and became British ambassador at Berlin and then Vienna during the Congress.

In 1819 he married the wealthy Frances Anne Vane Tempest who had inherited coal mines and a grand estate in County Durham. They travelled widely and rebuilt Wynyard, County Durham and Londonderry House in London. Charles also extended Mount Stewart in the 1840s.

His grandson, the 6th Marquess, was Lord Lieutenant of Ireland in the 1880s. The 6th Marquess was strongly opposed to Home Rule for Ireland; he and his wife were instigators and signatories of the Ulster Covenant in 1912.

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

The 7th Marquess

Charles’s great-grandson, Charles 7th Marquess, served in the First World War, during which his wife Edith founded the Women’s Legion. At the end of the war, Edith began to create the gardens at Mount Stewart and redecorated and furnished the house, processes she thoroughly enjoyed and continued until her death in 1959.

Charles served in the new Northern Irish government following the partition of Ireland in 1921. He later became Secretary of State for Air during the early 1930s.

The horrors of the First World War and the rise of Communism meant many were anxious to avoid another European war. For Charles, this meant holding a series of meetings with the Nazi leadership, but his actions and intentions were misunderstood and his career and reputation were fatally damaged.

These historic, sometimes seismic, events are woven into Mount Stewart and there are many objects, books and paintings in the house that connect us to the people who experienced, influenced and formed them.

Present day

Restoration of the house

2015 saw the completion of an extensive restoration of the house and its contents as well as the purchase of the wider estate re-uniting it with plans to open more trails to the public.

Expanding the estate

The present-day estate of Mount Stewart extends to 950 acres with a large lake and many monuments and farm buildings with plans to open more trails in future.

A family walking across the garden lawn surrounded by flower beds and hedges at Mount Stewart, with a view of the house in the background

Discover more at Mount Stewart

Find out when Mount Stewart is open, how to get here, things to see and do and more.

You might also be interested in

Two women walking in the Central Hall of the House

Step inside the house at Mount Stewart 

Explore the historic house and wander through the elegant rooms to discover a much-loved family home, filled with magnificent portraits and personal treasures.

Visitors stopping to enjoy the view of Srtangford Lough from Mount Stewart, County Down

Exploring the estate at Mount Stewart 

Pull on your walking boots, choose your route and head out for a walk on the Mount Stewart estate. Spot seasonal wildlife as you go, or run wild in the natural play area.

Visitors walking their dog in the parkland at Calke Abbey, Derbyshire

Visiting Mount Stewart with your dog 

Discover Mount Stewart with your dog. With acres of parkland to explore there's plenty of space for them to bound, sniff, jump and splash. Mount Stewart is a two pawprint rated place.

Overhead view of an octagonal table with the figure of Silenus, a drunken follower of Bacchu, in The Library at Claydon House in Buckinghamshire


Learn about people from the past, discover remarkable works of art and brush up on your knowledge of architecture and gardens.

Octavia Hill (1838 - 1912) (after John Singer Sargent) by Reginald Grenville Eves, RA (London 1876 ¿ Middleton in Teesdale 1941)


From landscape gardeners to LGBTQ+ campaigners and suffragettes to famous writers, many people have had their impact on the places we care for. Discover their stories and the lasting legacies they’ve left behind.

The silver collection on display in the Central Hall at Mount Stewart, County Down

Mount Stewart's collections 

Explore the objects and works of art we care for at Mount Stewart on the National Trust Collections website.