non, and first earl of Bessborough, by his first wife, Sarah, granddaughter of James Margetson [q. v.], archbishop of Armagh, and widow of Hugh Colvil, esq., of co. Down. William Ponsonby, second earl of Bessborough [q. v.], was his elder brother. His great-grandfather, Sir John Ponsonby, of Hale in Cumberland, born in 1608, commanded a troop of horse in the service of the Commonwealth, and had two grants of land assigned him in Ireland under the acts of settlement. He represented co. Kilkenny in parliament in 1661, and, dying in 1678, was succeeded by his son William [see under Ponsonby, Henry].
Ponsonby entered parliament in 1739 as member for the borough of Newtown, co. Down, vacated by the elevation of Robert Jocelyn, first viscount Jocelyn [q. v.], to the lord-chancellorship. Shortly afterwards, in 1742, he was appointed secretary to the revenue board, and, on the death of his father in 1744, succeeded him as first commissioner. He held the post with credit for twenty-seven years, and on his dismission in 1771 he received the unanimous thanks of the merchants of Dublin. On the occasion of the rebellion of 1745 he raised four independent companies of horse, and was specially thanked by Lord Chesterfield in the king's name for his loyalty. Besides being the first to be raised at that time, his troopers were notable for their discipline and handsome uniform, which, with the exception of the sash, was the same for the men as the officers. In 1748 he was sworn a privy councillor, and on 26 April 1756 was unanimously elected speaker of the House of Commons in succession to Henry Boyle, created lord Shannon [q. v.] (cf. a curious account of his election in Letters from an Armenian, &c. p. 45, attributed to Edmond Sexton Pery [q. v.]).
Ponsonby's connection by marriage with the Duke of Devonshire and the great parliamentary influence of his own family rendered him an important political factor in a country of which the government practically lay in the hands of three or four great families. On the change of administration which occurred shortly after his election to the speakership, Ponsonby entered into an alliance with the primate, George Stone [q. v.], with the object of securing a dominant influence in state affairs. In this he was successful. For the commons having, in October 1757, passed a strong series of resolutions against pensions, absentees, and other standing grievances, the lord lieutenant, the Duke of Bedford, who had formed the design of governing independently of the undertakers, was, much against his will, compelled by a threat of suspending supplies to transmit them to England in the very words in which they had been moved. This was regarded as a great triumph for the speaker, and on the departure of the viceroy in May 1758, he had the satisfaction of being included in the commission for government along with the primate and the Earl of Shannon. Several unsuccessful attempts were made to diminish his power, especially during the viceroyalty of the Earl of Northumberland in 1763–4, but nothing occurred to permanently shake his authority till the arrival of the Marquis of Townshend in 1767. In 1761 he was returned for Armagh borough and the county of Kilkenny, but elected to serve for the latter, which he continued to represent till 1783.
The appointment of the Marquis of Townshend as resident viceroy marks the beginning of a new epoch in Irish history. Hitherto it had been the custom of the lord lieutenant for the time being to spend only two or three months during the year in Dublin for the purpose mainly of conducting the business of parliament. In consequence of this arrangement the government of the country had for many years rested in the hands of a few families, among whom the Ponsonbys were pre-eminent; they practically controlled parliament, and for their service in managing the king's business—whence the name ‘undertakers’—were allowed to engross to themselves the chief emoluments in the country. So far, indeed, as Ireland was concerned, there had hitherto been little to complain of in regard to this arrangement. But in England the growing independence of the Irish parliament was regarded with increasing suspicion. The appointment of Townshend was intended as a blow against the authority of the ‘undertakers,’ and all the influence of the crown was accordingly placed at his disposal. Immediately on his arrival he set himself resolutely to form a party in parliament wholly dependent on the crown. The Octennial Bill was a serious blow to the dominion of the undertakers. Ponsonby and his friends instantly recognised the danger that menaced them, and by their united effort succeeded in frustrating the viceroy's attempt to force through parliament a money bill, which had taken its origin in the privy council. For this he was immediately deprived of his office of commissioner of revenue, and the effect of his punishment was such that at the close of the session parliament passed a vote of thanks to the viceroy. Rather, however, than consent to present an address so antagonistic to his feelings, Ponsonby preferred to resign the speakership (cf. Charlemont MSS. i. 39). He no doubt expected to be re-elected, but had the additional