Mary Stuart, Countess of Bute and 1st Baroness Mount Stuart (February 1718 – 6 November 1794) was the daughter of Edward Wortley-Montagu and Lady Mary Pierrepont

Lady Mary Wortley Montagu

The Lady Mary Wortley Montagu was an English aristocrat and writer. Montagu is today chiefly remembered for her letters, particularly her letters from Turkey, as wife to the British ambassador, which have been described by Billie Melman as “the very first example of a secular work by a woman about...

 (the daughter of the 1st Duke of Kingston-upon-Hull

Evelyn Pierrepont, 1st Duke of Kingston-upon-Hull

Evelyn Pierrepont, 5th Earl and 1st Duke of Kingston-upon-Hull had been member of parliament for East Retford before his accession to the peerage in 1690. While serving as one of the commissioners for the union with Scotland he was created Marquess of Dorchester in 1706, and took a leading part in...

).

On 27 August 1736, she married the future Prime Minister of the United Kingdom

Prime Minister of the United Kingdom

The Prime Minister of the United Kingdom of Great Britain and Northern Ireland is the Head of Her Majesty's Government in the United Kingdom. The Prime Minister and Cabinet are collectively accountable for their policies and actions to the Sovereign, to Parliament, to their political party and...

, John Stuart, 3rd Earl of Bute

John Stuart, 3rd Earl of Bute

John Stuart, 3rd Earl of Bute KG, PC , styled Lord Mount Stuart before 1723, was a Scottish nobleman who served as Prime Minister of Great Britain under George III, and was arguably the last important favourite in British politics...

 and had at least nine children by him:

1. Lady Mary Stuart (ca. 1741 – 5 April 1824), who married James Lowther
   James Lowther, 1st Earl of Lonsdale
   Sir James Lowther, 1st Earl of Lonsdale was the son of Robert Lowther and Catherine Pennington.He married Mary Crichton-Stuart, daughter of John Stuart, 3rd Earl of Bute and Mary Wortley-Montagu, 1st Baroness Mount Stuart on 7 September 1761.On 9 June 1792 he fought a duel with a Captain Cuthbert...
   
   , later the 1st Earl of Lonsdale
   Earl of Lonsdale
   Earl of Lonsdale is a title that has been created twice in British history, firstly in the Peerage of Great Britain in 1784 , and then in the Peerage of the United Kingdom in 1807, both times for members of the Lowther family....
   
   , on 7 September 1761
2. John Stuart, 1st Marquess of Bute
   John Stuart, 1st Marquess of Bute
   John Stuart, 1st Marquess of Bute, PC, FRS was a British nobleman.He was the son of the 3rd Earl of Bute and the former Mary Wortley Montagu, a granddaughter of the 1st Duke of Kingston-upon-Hull and great-granddaughter of the 1st Earl of Sandwich...
   
    (30 June 1744 – 16 November 1814)
3. Lady Anne Stuart (born ca. 1745), who married Lord Warkworth
   Hugh Percy, 2nd Duke of Northumberland
   Lieutenant-General Hugh Percy, 2nd Duke of Northumberland, FRS was an officer in the British army and later a British peer...
   
   , later the 2nd Duke of Northumberland
   Duke of Northumberland
   The Duke of Northumberland is a title in the peerage of Great Britain that has been created several times. Since the third creation in 1766, the title has belonged to the House of Percy , which held the title of Earl of Northumberland from 1377....
   
   , on 2 July 1764
4. The Hon. James Archibald Stuart (19 September 1747 – 1 March 1818)
5. Lady Jane Stuart (ca. 1748 – 28 February 1828), who married George Macartney
   George Macartney, 1st Earl Macartney
   George Macartney, 1st Earl Macartney, KB was an Irish-born British statesman, colonial administrator and diplomat. He is often remembered for his observation following Britain's success in the Seven Years War and subsequent territorial expansion at the Treaty of Paris that Britain now controlled...
   
   , later the 1st Earl Macartney, on 1 February 1768.
6. The Hon. Sir Charles Stuart (January 1753 – 25 May 1801)
7. The Most Rev. and Hon. William Stuart
   William Stuart (archbishop)
   The Most Reverend William Stuart PC, D.D. was an Anglican clergyman who served as Bishop of St David's in Wales from 1794 and 1800 and then Archbishop of Armagh in Ireland from 1800 to his death.-Family life:...
   
   , Archbishop of Armagh (Church of Ireland) (March 1755 – 6 March 1822)
8. Lady Caroline Stuart (before 1763 – 20 January 1813), who married The Hon. John Dawson, later the 1st Earl of Portarlington
   Earl of Portarlington
   Earl of Portarlington is a title in the Peerage of Ireland. It was created in 1785 for John Dawson, 2nd Viscount Carlow, who had earlier represented Portarlington in the Irish House of Commons...
   
   , on 1 January 1778.
9. Lady Louisa Stuart
   Lady Louisa Stuart
   Lady Louisa Stuart was a British writer of the 18th and 19th centuries. Her long life spanned nearly ninety-four years.-Early life:...
   
    (12 August 1757 – 4 August 1851)

In 1761, she was created Baroness Mount Stuart of Wortley

Wortley, South Yorkshire

Wortley is a village and civil parish in the Metropolitan Borough of Barnsley, South Yorkshire, England. At the 2001 census it had a population of 579.Wortley grew up as a settlement where the Sheffield to Halifax road crossed the Cheshire to Rotherham route...

, co. York and upon her death, was succeeded by her son, the 4th Earl of Bute

John Stuart, 1st Marquess of Bute

John Stuart, 1st Marquess of Bute, PC, FRS was a British nobleman.He was the son of the 3rd Earl of Bute and the former Mary Wortley Montagu, a granddaughter of the 1st Duke of Kingston-upon-Hull and great-granddaughter of the 1st Earl of Sandwich...

.

In 1774, Mary Delany

Mary Delany

Mary Delany was an English Bluestocking, artist, and letter-writer; equally famous for her "paper-mosaicks" and her lively correspondence.-Early life:...

 wrote to her friend Bernard Granville

Duke of Albemarle

The Dukedom of Albemarle has been created twice in the Peerage of England, each time ending in extinction. Additionally, the title was created a third time by James II in exile and a fourth time by his son the Old Pretender, in the Jacobite Peerage. The name is the Latinised form of the ancient...

:

Titles from birth to death

• Miss Mary Wortley Montagu (1718–1736)
• The Rt. Hon. The Countess of Bute (1736–1792)
• The Rt. Hon. The Dowager Countess of Bute (1792–1794)