Duncombe was one of the Yorkshire Association’s candidates for the county in 1780 and 1784. As such he supported Pitt’s administration. He was unopposed in 1790. His colleague Wilberforce being seldom in Yorkshire, he was the business Member for the county and even managed Wilberforce’s private concerns for him.
Duncombe had seconded Pitt’s plan of parliamentary reform in 1785. Presenting the Sheffield petition in its favour, 2 May 1793, he admitted that he was still ‘a friend of temperate reform’. He objected to piecemeal disfranchisements, such as those proposed at Stockbridge, 3 May; and four days later spoke in favour of Grey’s reform motion in principle, though he thought Grey was over indulgent to popular representation and he did not divide on it.
Duncombe approved precautions for the King’s safety, but could not swallow the bill against seditious meetings, 12 Nov. 1795, which undermined the ‘democratical’ part of the constitution. He supported the first reading in the hope that further discussion would reveal its objectionable tendencies. He concurred in Fox’s presentation of a petition from Halifax against it, 3 Dec., and next day presented a county petition to the same effect (countered by Wilberforce). On 15 Dec. he expressed his approbation of Fox’s defence of the character of Lord North, whom he had personally opposed. An advocate and founder member of the board of agriculture, he argued that potato growing was stimulated by the high price of other provisions, 29 Feb. 1796. Although he was an admirer of Sir John Sinclair’s exertions, he advised him to proceed more circumspectly with his general enclosure bill, 22 Apr. 1796.
Duncombe decided in January 1796 to retire at the next election, when his friend Rev. Christopher Wyvill informed him that the opposition of the Lascelles family, previously directed against Wilberforce, would in future be directed against him. His infirmity was excuse enough and he was conscious of having differed from public opinion in the county on the measures against sedition.
But the delusion of his constituents was too complete, and at his age the fatigues of the struggle which awaited him, would have been too severe, and probably would have been alike pernicious to himself and unavailing to the public.
He duly retired at the dissolution, when he was denied the satisfaction of seeing his nephew Charles Duncombe succeed him. One of Wyvill’s friends deplored the loss of ‘a useful steady Member’ whose ‘independence of spirit’ was admirable.
