William Cavendish-Bentinck, 3rd Duke of Portland

His Grace The Duke of Portland KG PC FRS
Portrait by Thomas Lawrence c. 1792
Prime Minister of the United Kingdom
In office 31 March 1807 – 4 October 1809
Monarch	George III
Preceded by	The Lord Grenville
Succeeded by	Spencer Perceval
Prime Minister of Great Britain
In office 2 April 1783 – 18 December 1783
Monarch	George III
Preceded by	The Earl of Shelburne
Succeeded by	William Pitt the Younger
Lord President of the Council
In office 30 July 1801 – 14 January 1805
Prime Minister	Henry Addington William Pitt the Younger
Preceded by	The Earl of Chatham
Succeeded by	The Viscount Sidmouth
Home Secretary
In office 11 July 1794 – 30 July 1801
Prime Minister	William Pitt the Younger
Preceded by	Henry Dundas
Succeeded by	Lord Pelham
Leader of the House of Lords
In office 2 April 1783 – 18 December 1783
Prime Minister	Himself
Preceded by	The Earl of Shelburne
Succeeded by	The Earl Temple
Lord Lieutenant of Ireland
In office 8 April 1782 – 15 August 1782
Prime Minister	The Earl of Shelburne
Preceded by	The Earl of Carlisle
Succeeded by	The Earl Temple
Lord Chamberlain of the Household
In office 1765–1766
Monarch	George III
Preceded by	The Earl Gower
Succeeded by	The Earl of Hertford
Personal details
Born	(1738-04-14)14 April 1738 Bulstrode Park, Gerrards Cross, Buckinghamshire, England
Died	30 October 1809(1809-10-30) (aged 71) Westminster, England
Resting place	St Marylebone Parish Church
Political party	Whig (Foxite) (1761–1794) Tory (Pittite) (1794–1809)
Spouse	Lady Dorothy Cavendish ​ ​ (m. 1766; died 1794)​
Children	6, including William, 4th Duke; Lord William and Lord Charles
Parents	William Bentinck, 2nd Duke of Portland Margaret Cavendish-Harley
Alma mater	Christ Church, Oxford
Signature

William Henry Cavendish Cavendish-Bentinck, 3rd Duke of Portland, KG, PC, FRS (14 April 1738 – 30 October 1809) was a British Whig and then a Tory politician during the late Georgian era. He served as chancellor of the University of Oxford (1792–1809) and as Prime Minister of Great Britain (1783) and then of the United Kingdom (1807–1809). The gap of 26 years between his two terms as prime minister is the longest of any British prime minister. He was also the fourth great-grandfather of King Charles III through his great-granddaughter Cecilia Bowes-Lyon, Countess of Strathmore and Kinghorne.

Portland was known before 1762 by the courtesy title Marquess of Titchfield. He held a title for every degree of British nobility: duke, marquess, earl (Earl of Portland), viscount (Viscount Woodstock), and baron (Baron Cirencester). He was the leader of the Portland Whigs faction, which broke with the Whig leadership of Charles James Fox and joined with William Pitt the Younger in the wake of the French Revolution.