William Henry Cavendish-Bentinck, 3rd Duke of Portland, KG, PC (14 April 1738 – 30 October 1809) was a British Whig and Tory , Chancellor of the University of Oxford and twice Prime Minister of Great Britain, serving in 1783 and again from 1807 to 1809. The 24 years between his two terms as Prime Minister is the longest gap between terms of office of any Prime Minister.