Adams rallied to Pitt’s administration in his first Parliament, sitting on the Buller interest. In 1790 and 1796 he was returned as a guest on the Calthorpe interest at Hindon and Bramber. He seldom spoke in debate, but not infrequently acted as teller for the government. He was listed hostile to the repeal of the Test Act in Scotland in 1791. On 26 Jan. 1795 he briefly opposed peace negotiations and on 4 Jan. 1798 supported Pitt’s assessed taxes. He had subscribed £5,000 to the loyalty loan for 1797 and his brother Charles £2,000. Although never particularly close to his brother-in-law Addington, he was appointed a lord of the Admiralty by the latter on taking office in 1801. He was occasionally obliged to bring up Admiralty business in the House, but took no great interest in it: he was absent from the board meeting of 20 Aug. 1802 which launched the inquiry into the management of the dockyards. He had heedlessly taken a holiday and St. Vincent had to insist that he should at least attend the proceedings at Chatham and Sheerness, the yards nearest his home.
Adams joined Addington in opposition in 1804, voting against Pitt’s additional force bill in June. He voted with the majority for the criminal prosecution of Melville, 12 June 1805. His brother-in-law did not obtain any office for him in the Grenville ministry in 1806, but he voted with them for the repeal of Pitt’s Additional Force Act, 30 Apr. Lord Grenville could not be persuaded to let two Addingtonians come in for Harwich at the election of 1806 and Adams was obliged to make way for Hiley Addington and a Treasury nominee. His brother Charles was reluctant to sacrifice his seat for Weymouth to him. He was still ambitious for office, but his brother-in-law concluded that ‘office and a seat, under such circumstances as the present, is more than could be expected except for a person more immediately connected with the minister’.