Lord Dupplin was successively the faithful servant of Sir Robert Walpole, Henry Pelham, and the Duke of Newcastle. In 1754 he was returned unopposed for Cambridge, a borough managed for Government by Dupplin and Lord Montfort. He had been employed by Pelham on election business and in 1754 had to explain to Newcastle all Pelham’s plans for the forthcoming general election. After the election he drew up for Newcastle a list of the House of Commons arranged according to political allegiances. He was also an expert on finance, and in this also he was Newcastle’s mentor at the Treasury. ‘Lord Dupplin aimed at nothing but understanding business and explaining it’, wrote Horace Walpole, reviewing in 1755 the leading speakers in the House of Commons.
But Kinnoull (as Dupplin became in 1758) was not made for Opposition and knew it. On Newcastle’s resignation he told George III he would support whatever minister the King should name. When the Duke of Devonshire was dismissed, Kinnoull resigned his office from his ‘inviolable friendship’ to Devonshire, but refused to go into opposition.
He died 27 Dec. 1787.
