O'BRIEN, William, 4th Earl of Inchiquin [I] (c.1700-77).

Published in The History of Parliament: the House of Commons 1715-1754, ed. R. Sedgwick, 1970
Available from Boydell and Brewer



1722 - 1727
1727 - 1734
1741 - 1747
1747 - 1754

Family and Education

b. c.1700, 1st s. of William O’Brien, 3rd Earl of Inchiquin [I], by Mary, da. of Sir Edward Villiers, knight-marshal, sis. of Edward Villiers, 1st Earl of Jersey. m. (1) 28 Mar. 1720, his 1st cos. Lady Anne Hamilton (d. 6 Dec. 1756), da. and h. of George Hamilton, 1st Earl of Orkney [S], and suo jure Countess of Orkney, 4s. 4da.; (2) 12 Oct. 1761, Mary, da. of Stephen Moore, 1st Visct. Mount Cashell [I], s.p. suc. fa. 24 Dec. 1719; K.B. 28 May 1725.

Offices Held

Grand master of freemasons 1740-1; gov. co. Clare 1741 and custos rot. 1762-d.; gent. of the bedchamber to Frederick, Prince of Wales Dec. 1744-51; P.C. [I] 15 Nov. 1753.


Succeeding to an estate of £9,000 p.a.,1 Inchiquin took his seat in the Irish House of Lords in September 1721. Returned on the government interest for Windsor in 1722 and on the interest of his first cousin, the 2nd Viscount Weymouth, for Tamworth in 1727, he voted with the Administration on the civil list in 1729, but went into opposition the following year. At a meeting of Irish gentlemen to consider matters before Parliament relating to Ireland in April 1731, he is mentioned as always voting against the ministry.2 In 1734 he was not put up for Tamworth, where he stood unsuccessfully at a by-election in 1735. Returned for Camelford in 1741 on the recommendation of Frederick, Prince of Wales, whose household he entered in 1744,3 he voted against the Administration on the chairman of the elections committee in 1741, but for them on the Hanoverians in 1742, 1744 and 1746, reverting to opposition with his master in 1747, when he was returned for Aylesbury. Affected with an impediment in his speech which caused him to stutter,4 he is not known to have spoken in the House. Losing his place on Frederick’s death, he did not stand again. He died 18 July 1777.

Ref Volumes: 1715-1754

Author: Eveline Cruickshanks


  • 1. HMC Carlisle, 232.
  • 2. HMC Egmont Diary, i. 169-70.
  • 3. HMC Fortescue, i. 108.
  • 4. Walpole, Mems. Geo. II, iii. 241.