Cavendish, Sir Henry (1732–1804), politician and parliamentary reporter, was born 29 September 1732, eldest of six children of Henry Cavendish (qv) of Doveridge Hall, Derbyshire, teller of the Irish exchequer (1755–76) and MP, and Anne Cavendish (née Pyne) of Waterpark, Co. Cork, granddaughter of Sir Richard Pyne, lord chief justice of Ireland. The family was of illegitimate descent from Henry, brother of the 1st earl of Devonshire. His father came to Ireland with the 3rd duke of Devonshire (qv), viceroy (1737–45), and Henry spent some of his childhood in Ireland. He was educated at Eton (1747–8) and briefly attended TCD (1750). Through the influence of the 3rd duke of Devonshire, he became MP for Lismore (1766–8, 1776–90, 1798–1800); he was also MP for Killybegs, Co. Donegal (1790–97). He sat in the British parliament for Lostwithiel, Cornwall (1768–74), generally supporting the opposition Rockingham whigs. At Westminster he took copious notes in Gurney's shorthand of the debates of the ‘unreported parliament’ (1768–74). These manuscripts, amounting to almost 16,000 pages and containing speeches from most of the leading statesmen of the day, are now in the British Library, and some portions of them have been published. Proud of his Irish connections, he paid considerable attention to Irish matters at Westminster. On his father's death in 1776 he succeeded to the baronetcy and returned to Ireland, taking up residence at Waterpark. He was left with debts of about £67,000 because of his father's mismanagement of exchequer funds, and gradually repaid them over the rest of his life. In 1779 he was made receiver general of customs for Ireland and appointed to the Irish privy council. In the Irish commons he again kept a diary of debates (thirty-seven longhand volumes of 10,646 pages, now in the Library of Congress, Washington, DC). He appears to have generally recorded these debates with a high level of accuracy, and since the Parliamentary register (20 vols, Dublin, 1784–1800) only covered debates from 1781, his diaries are a crucial source for the 1776–81 period. His achievement was such that he has been described as ‘the father of Hansard’ (Malcomson, 128).
As a speaker he was often dry and sarcastic, at his best in debates on finance, but better at picking holes in an opponent's argument than putting forward a persuasive case himself. His recording of debates often gave him an advantage, and other members regularly asked to see his transcripts. Skilled in parliamentary rules and procedures, he was adept at countering arguments with precedents and raising points of order to interrupt opponents or gain time, which made him very unpopular with the public gallery; he was once even hissed by the public when he rose to speak. In 1780 he strongly criticised the rise of the Volunteer movement and was prominent in attempting to block the efforts of Patriot spokesmen to abolish restrictions on Irish trade. A list of members in 1782 noted that he was ‘a good shorthand writer but a tiresome speaker’ (Sayles, 268), while Wolfe Tone (qv) described him as ‘a notorious slave of the house of commons’ (Tone, ii, 285). He briefly supported the opposition Ponsonby connection, voting with them for a regency (1789), but defected to the government in 1790 with his three sons. He and his sons all purchased parliamentary seats during the 1790 general election. In 1793 his revenue post was abolished but he was appointed vice-treasurer and commissioner of the Irish treasury (25 December 1793), lord commissioner of the treasury (1795) and paymaster general (1795–9). He was the author of A statement of the public accounts of Ireland (1791). In 1795 he was chosen as chairman of a committee to oversee the printing of the Irish commons’ journals and made several valuable recommendations for their improvement. Although he was generally considered vain and excessively ambitious, his perseverance was admired. John Scott (qv) noted that despite ‘a slight frame and very moderate powers, by mere assiduity [he] made himself the first sailor, skater, billiard-player, fiddler, shorthand writer and master of several other accomplishments of any man in Britain’ (Fitzpatrick, 20–21). Such tenacity largely explains the painstaking diligence of his parliamentary reporting. From 1790 he consistently supported the government, and he and his son George voted in favour of the act of union in 1799 and 1800. He died 3 August 1804 at Blackrock, Co. Dublin.
He married (29 August 1757) Sarah (1740–1807), only daughter and heiress of Richard Bradshaw of Cork, who in 1792 became Baroness Waterpark as a reward for her husband's support of the government; they had four sons and four daughters, including Richard (1765–1830), MP for Portarlington, and Baron Waterpark (1807–30); George (1766–1849), MP for St Johnstown, Co. Longford (1790–97) and Cavan borough (1798–1800); and Augustus Cavendish Bradshaw (1768–1832), MP for Carlow borough (1790–96), and for the English boroughs of Honiton (1805–12), and Castle Rising (1812–17).