1743, Henry Pelham became prime minister; but Carteret remained in the ministry, and Chesterfield pursued him with much the same rancour as he had pursued Walpole. In the House of Lords he was now the acknowledged leader of the opposition, and played much the same role there that Pitt was playing in the House of Commons. In January 1744 he supported the proposal to discontinue the pay to the Hanoverian troops. 'The crown of three kingdoms,' he said, 'was shrivelled beneath an electoral cap.' To one outside observer Chesterfield's strenuous hostility to George II and his government had given unalloyed satisfaction. The Dowager Duchess of Marlborough had watched with enthusiasm the action of Chesterfield in the lords and Pitt in the commons, and when she died, on 17 Oct. 1744, she left Chesterfield a legacy of 20,000l. 'out of the great regard she had for his merit, and the infinite obligations she received from him on account of his opposition to the ministry.' Pitt, on the same ground, received 10,000l.
In the autumn of 1744 long-pending dissensions in the cabinet came to a head. Pelham and the Duke of Newcastle resolved to drive Carteret from office, and approached Chesterfield with a view to his co-operation. Although Carteret had the king's full confidence, he felt it useless to resist the combined attack, and on 24 Nov. 1744 he resigned the seals. His friends followed his example. Thereupon, in accordance with Chesterfield's known views, a new administration was formed of members drawn from both the whig and tory parties. It was at once christened, after the pseudonym that he had invented, the ' Broad-bottom administration.' Pelham retained his place as prime minister, and the king was reluctantly compelled to confer on Chesterfield the high office of lord-lieutenant of Ireland. Before he took up that post the government resolved to send him on an important diplomatic mission to The Hague, where his name was still favourably remembered. The king was with difficulty 'brought to give him a parting audience.' It did not last forty-five seconds. 'You have received your instructions, my lord,' was all that was said. Chesterfield's appointment bore date 12 Jan. 1745. His instructions were to induce the Dutch to join in the war of the Austrian succession, and to determine the number of troops they would supply. The French envoy, the Abbé de la Ville, was at The Hague before Chesterfield; but Chesterfield, while treating him with the utmost ease and politeness, successfully completed the negotiations in his country's interest. Their course can be traced in detail in Chesterfield's correspondence with the Duke of Newcastle and Lord Harrington, the secretary of state, now in the British Museum (Ernst, pp. 219-39). Chesterfield returned home at the end of May, prepared to inaugurate his reign in Ireland.
Chesterfield arrived in Dublin in July, and, although his viceroyalty lasted only eight months, it proved him to be a tactful and enlightened statesman. His character had affinity to that of the Irish people, and he viewed them sympathetically. When he arrived the Scottish rebellion of 1745 was imminent; but while urging on the government in London the most rigorous measures of repression in England and Scotland, and neglecting no precaution to stay the possible spread of the contagion to Ireland, he was not surprised by panic into one needless act of coercion. With happy ridicule he discouraged the rumours of popish risings. Ireland, he said, had much more to fear from her poverty than her popery, and Miss Ambrose, the reigning beauty in Dublin society, to whom he addressed some witty flattery in verse, was the only dangerous papist he knew of [see Palmer, Eleanor, Lady]. He firmly refused to follow the precedent of 1715, when all the catholic chapels were closed during the Jacobite outbreak, and to his prudent counsels must be attributed Ireland's tranquillity at a time when England and Scotland were torn by civil war (Lecky, Hist, of Ireland in the Eighteenth Century, i. 460-1). The main objects of his government were to raise the material prosperity of the country and to distribute public patronage in the public interest. 'He wished,' he wrote, 'to be remembered by the name of the Irish lord-lieutenant.' With the landlords he disavowed all sympathy, and ridiculed their improvidence and extravagant consumption of claret. He declared that 'the poor people in Ireland' were worse used than negroes by their lords and masters, 'and their deputies of deputies of deputies.' He sought to relieve public distress by undertaking public works. The planting of Phœnix Park was one of his projects.
On 23 April 1746 he left Ireland on leave of absence, and a long illness prevented his return. He had not entirely recovered in September. But the ministry stood in need of his active help, and the king was growing better disposed towards him. Chesterfield's position compelled him outwardly to support the court, and in February 1746 a caricaturist represented him along with Pitt as receiving a reprimand for his complaisance
