Career
A prominent Whig, he was sworn of the Privy Council in 1707, and served as Lord President of the Council from 1716 to 1717 and 1725 to 1729. Rachel Russell (1674–1725), daughter of William, Lord Russell on 21 June 1688. They had five children:
William Cavendish, 3rd Duke of Devonshire (26 September 1698 – 5 December 1755)
Lady Rachel Cavendish (4 October 1699 – 18 June 1780) married Sir William Morgan on 14 May 1723
Lady Elizabeth Cavendish (27 September 1700 – 7 November 1747) married Sir Thomas Lowther, 2nd Baronet
Lord James Cavendish (23 November 1701 – 14 December 1741)
Lord Charles Cavendish (17 March 1704 – 28 April 1783) married Anne Grey on 9 January 1727, father of Henry Cavendish
Sir William also had an illegitimate child:
Henrietta Cavendish (c1684 – 11 January 1717) married Lionel Tollemache, Lord Huntingtower, son of Lionel Tollemache, 3rd Earl of Dysart and Grace Wilbraham.