Biography of William Henry Cavendish Cavendish-Bentinck, 3rd Duke of Portland (1738-1809)
- [Hans] William Bentinck, 1st Earl of Portland (1649-1709)
- [William] Henry Bentinck, 1st Duke of Portland (1682-1726)
- William Bentinck, 1st Count Bentinck (1704-1774)
- Charlotte Sophie, Countess Bentinck, née Countess of Aldenburg (1715-1800)
- William Bentinck, 2nd Duke of Portland (1709-1762)
- Margaret Cavendish-Bentinck, Duchess of Portland (1715-1785)
- John Albert Bentinck (1737-1775; naval captain and M.P.)
- William Henry Cavendish Cavendish-Bentinck, 3rd Duke of Portland (1738-1809)
- William Bentinck (1764-1813; Vice-Admiral)
- William Henry Cavendish-Scott-Bentinck, 4th Duke of Portland (1768-1854)
- Lord William Henry Cavendish-Bentinck (1774-1839; M.P. and Governor General of India)
- William John Cavendish-Bentinck-Scott, 5th Duke of Portland (1800-1879)
- Lord [William] George Frederic Cavendish-Scott-Bentinck (1802-1848)
- Lord [William] Henry Cavendish-Bentinck (1804-1870)
- William John Arthur Charles James Cavendish-Bentinck, 6th Duke of Portland (1857-1943)
- Winifred Anna Cavendish-Bentinck, Duchess of Portland (1863-1954)
- William Arthur Henry Cavendish-Bentinck, 7th Duke of Portland (1893-1977)
- Ferdinand William Cavendish-Bentinck, 8th Duke of Portland (1888-1980)
- Victor Frederick William Cavendish-Bentinck, 9th Duke of Portland (1897-1990)
- Henry Noel Bentinck, 11th Earl of Portland (1919-1997)
- Timothy Charles Robert Noel Bentinck, 12th Earl of Portland (b 1953)
William's education followed the emerging family tradition of attendance at Westminster School and then Oxford University. On leaving university he embarked on the 'Grand Tour', taking in countries including Poland, Germany and Italy. He was soon to enter the political fray, however, being elected as M.P. for Weobly in 1761. In spite of his later political achievements, he apparently made very little impact during his time in the House of Commons.
Following his elevation to the House of Lords, the 3rd Duke's political influence developed quickly. He aligned himself with the Whigs and in 1765 became Lord Chamberlain in Rockingham's ministry. After Rockingham's ministry fell, Portland played an influential role in organising the party and used his extensive electoral influence to secure the return of a number of M.P.s. It was to be sixteen years, however, before he returned to government with Rockingham, in 1782. When, in that same year, Rockingham died, the 3rd Duke of Portland was surprised to be chosen as party leader. He found himself at the head of a coalition government as First Lord of the Treasury, or Prime Minister. By the end of 1783, however, the coalition government had been dismissed, and Portland found himself in opposition once again, by this time, closely allied with Fox.
In 1793, after a bitter struggle within the Whig party, Portland's political alliance with Fox was broken. After protracted manoeuvrings, Portland and his followers managed to secure five cabinet places in the Pitt administration. This gave them a share of power which had previously seemed unobtainable. Portland himself became Home Secretary, a post which he was to hold until 1801. His tenure at the Home Office coincided with the Irish Union, and it seems that the 3rd Duke was a central figure in secret negotiations to secure the passing of the legislation.
In the later years of his political career the 3rd Duke of Portland began to move towards the emerging 'Toryism'. He was hostile to both parliamentary reform and to Catholic Emancipation and remained a loyal supporter of the royal prerogative. In 1807, Portland once again held the post of First Lord of the Treasury, though his age and illnesses really meant he was unfit for the task. He resigned the post in 1809 against a background of clandestine negotiations to reorganise the cabinet, and died shortly afterwards after undergoing an operation to remove a kidney stone.
William Henry Cavendish-Bentinck, 3rd Duke of Portland
In 1766 he married Lady Dorothy Cavendish (1750-1794), daughter of the 4th Duke of Devonshire, and by her had:
- William Henry (1768-1854), later 4th Duke of Portland
- William Henry (1774-1839), known as Lord William Bentinck
- William Charles Augustus (1780-1826)
- Frederick (1781-1828). The 8th Duke of Portland was his descendant.
- Charlotte (1775-1862) m Charles Greville in 1793
- Mary (1778-1843) died unmarried
- The 3rd Duke's papers (Pw F) are part of the Portland (Welbeck) Collection held in Manuscripts and Special Collections at The University of Nottingham and include personal, political and estate correspondence
- The Portland (London) Collection (Pl), also held in Manuscripts and Special Collections at The University of Nottingham, contains correspondence and official papers of the 3rd Duke, especially in series Pl C.
- The Portland Estate Papers held at Nottinghamshire Archives also contain items relating to the 3rd Duke's properties
- Details of collections held elsewhere are available through the National Register of Archives.
- Turberville, A.S., A History of Welbeck Abbey and its Owners, Volume 2, Chapters 3-14 (London, 1938) [King’s Meadow Campus East Midlands Collection Not 468.D14 TUR]
- Wilkinson, David, The Duke of Portland : politics and party in the age of George III (Basingstoke, 2003) [King's Meadow East Midlands Collection Not 468.V38 POR]
- Ross, David F., William Henry Cavendish Bentinck, Third Duke of Portland : the years in opposition, 1738-1794 (PhD Thesis, University of Chicago, 1991)
- Wilkinson, David, The political career of William Henry Cavendish-Bentinck, Third Duke of Portland, 1738-1809 (PhD Thesis, University of Wales Aberystwyth, 1997)