William Brabazon Ponsonby, 1st Baron Ponsonby (of Imokilly), PC (Ire) (15 September 17445 November 1806) was a leading Irish Whig politician, being a member of the Irish House of Commons, and, after 1800, of the United Kingdom parliament. Ponsonby was the son of the Hon. John Ponsonby, the Speaker of the Irish House of Commons and Lady Elizabeth Cavendish, daughter of the 3rd Duke of Devonshire. He was invested as a Privy Counsellor of Ireland in 1784. He served as Joint Postmaster-General of Ireland (1784–1789). Political career Ponsonby was educated at Trinity College, Cambridge. He represented Cork City between 1764 and 1776 and thereafter Bandonbridge between 1776 and 1783. He was the leader of a powerful family grouping of between ten and fourteen MPs, the second largest in the Irish House of Commons. During the regency crisis of 1788–89, he gave his support to the Prince of Wales in opposition to William Pitt the Younger. As a consequence, he was dismissed from the Post Office. Thereafter he permanently aligned himself with Charles James Fox and together with his brother George gathered together the various small groups of Irish whigs into a unified opposition. As with their English counterparts, their ultimate objective was to re-establish the influence of the landowning classes at the expense of the crown. Ponsonby became committed to the cause of Catholic Emancipation, as a means of securing a loyal population at a time of radical agitation and potential foreign invasion. Pitt's coalition with the Portland whigs in July 1794 and Earl FitzWilliam's consequent appointment as Lord Lieutenant of Ireland gave Ponsonby and his allies an opportunity to regain office. He was on the brink of becoming Irish secretary of state and had sat on the Treasury bench. In 1795, however, he appears to have persuaded FitzWilliam to dismiss John Beresford from his post as first commissioner of the revenue on the grounds of alleged corruption, apparently in revenge for earlier political dealings. The subsequent political crisis led in 1795 to FitzWilliam's swift removal from office, Beresford's reinstatement, and to Ponsonby's humiliating return to opposition. Ponsonby was a leading opponent of the union between Ireland and Great Britain. In 1783, he stood for Newtownards and Kilkenny County. He chose the latter constituency and sat for it from 1783 until the Act of Union came into force in 1801. He became then part of the Foxite Whig opposition in