Henry Cavendish was descended from an illegitimate son of Henry, elder brother of William Cavendish, 1st Earl of Devonshire. The family had estates in Derbyshire, and Cavendish’s father had some connexion with the 3rd Duke of Devonshire, who, after Cavendish had settled on his wife’s estates in Ireland, returned him to the Irish House for Lismore, which Henry Cavendish also in turn represented.
In 1768 Cavendish was returned for Lostwithiel on the interest of his cousin, Lord Edgcumbe. From the beginning of the Parliament he took shorthand notes of the debates, which he intended one day to publish.
In Parliament Cavendish regularly voted with the Opposition, and spoke against Administration on every political issue during his first years in the House. He vigorously attacked the Government’s handling of the Middlesex election, and on 8 May 1769 declared:
I lay it down as a principle that no order of the House of Commons can make a minority a majority; that no resolution of the House of Commons can ever make Mr. Luttrell the legal representative of the county of Middlesex. For I do from my soul abhor, detest, and abjure, as unconstitutional and illegal that damnable doctrine and position that a resolution of the House of Commons can make, alter, suspend, abrogate or annihilate the law of the land. I think myself bound in duty to support the violated privileges of the freeholders. I will take every moderate, legal, and constitutional step for that purpose; if all these means will not succeed, rather than they should be thus wantonly and illegally torn from them, I would arm in their defence.
Cavendish, whom Horace Walpole described as ‘hot-headed and odd’,
After the outbreak of disturbances in America, Cavendish, who had not previously spoken on American affairs, supported the Administration’s punitive measures. On 14 Mar. 1774 he came out in favour of the motion for leave to bring in the Boston port bill,
During his term at Westminster, Cavendish paid considerable attention to Irish interests. But when on 11 Dec. 1770 his complaints about the high price of provisions in Ireland drew a taunt from Dempster, Cavendish at once answered: ‘I rise as an English Member, though I am not ashamed to say I drew my first breath in Ireland; but my stake, such as it is, is much greater in England than in Ireland. I speak for the good of the community. I hope no distinctions will prevail as to English or Irish Members.’
He died 3 Aug. 1804.
