Cunynghame’s father, a distinguished soldier, contested Linlithgowshire in 1761, and as early as 1764 announced his candidature against the Hopetoun interest at the next election.
After the death of his wife in 1771 Cunynghame spent much time abroad, in Italy, Paris and Vienna,
In the Parliament of 1780-4 no speech by him is recorded. He consistently voted with North to the end of his Administration; voted against Shelburne’s peace preliminaries, 18 Feb. 1783; and for Fox’s East India bill, 27 Nov. 1783. In December, shortly before Pitt took office, Robinson counted him ‘contra’, but possibly ‘pro’ in a new Parliament:
Sir William Cunynghame is at present warm in support of the Administration. If he comes in he may not be quite steady, though most probably will be so, because he leans to Lord Mountstuart and affects to go as that family does; but a word from Lord Hopetoun might set this right both now and in future.
Nevertheless he remained against Pitt to the end of the Parliament, when Henry Dundas used all his influence without success to replace him in Linlithgowshire.
Cunynghame, impervious to the ridicule of Pitt and Dundas, and even, on occasion, the admonitions of his friends, stood forth as the indefatigable champion of Scottish interests. Determined to ‘give a brain blow’ to the application of the coal tax in Scotland, he pressed a division on 1 July 1784; strongly supported the forfeited estates bill on 2 Aug. 1784; opposed, 4 Aug., on behalf of the Scots manufacturers, the new duties on cotton and linen, and was vehement against the window tax as oppressive to Scotland. In 1785 he campaigned in and outside the House against Pitt’s Irish propositions as ruinous to the Scottish linen industry, corn trade, and fisheries. Strongly opposed to the abortive plan for reducing the number of Scottish judges, he actively supported in 1786 the proposed augmentation of their salaries, and unsuccessfully moved an amendment for a further increase commensurate with the emoluments of English judges. He won great popularity in Scotland, and exasperated Pitt, by his vehement support of the Scots distilling interests in the measures of 1785, 1786 and 1788. He consistently voted against Administration.
Defeated in 1790 by the Government-sponsored Hopetoun interest, he did not re-enter Parliament. He died 17 Jan. 1828.
