Ponsonby was returned for Kilkenny in succession to his father on the Bessborough interest and a few months afterwards for Cork, in succession to his cousin Viscount Boyle, though there was some idea of his standing for the King’s or the Queen’s County.
On his uncle’s death in 1817 there was surprise in some Whig circles that Earl Fitzwilliam did not return Ponsonby for the vacant seat for Wicklow, but failing this, Ponsonby set his heart on recapturing his seat for Cork from Richard Hare. His uncle Earl Grey encouraged him and he persuaded a reluctant Duke of Devonshire to assist him, but the election of 1818 came too soon to enable him to muster enough votes and he gave up the contest.
