The scion of a military family with estates and political interests in the Lowlands of Scotland, Dalrymple had joined the army as intended in 1799, but his career faltered after his father, whom he served as secretary in Portugal, signed the unpopular Convention of Cintra in 1808. An anti-Catholic Tory, he had been returned for Weymouth in 1817 and Lord Lonsdale’s seat at Appleby in 1819 on the recommendation of his father-in-law Sir James Graham, Member for Carlisle, and remained Member for Appleby in the 1820 Parliament. As hitherto, he generally divided with the Lowther ‘ninepins’ in support of the Liverpool administration’s policies on taxation and retrenchment and against Catholic relief, 28 Feb. 1821, 30 Apr. 1822, 1 Mar., 21 Apr., 10 May 1825.
On 4 May 1820 he countered Hume’s assertion that additional church provision was necessary in Gibraltar by describing the half-empty churches there during his residence, 1808-10. He divided consistently with government on the Queen Caroline affair, 1820-1, and voted to retain the death penalty for forgery offences, 23 May 1821. He approved the army estimates, 15 Mar. 1822, but his remarks were not reported.
He divided against Catholic relief, 6 Mar. 1827, 12 May 1828. He disputed the charges of mismanagement levelled against his friend Lord Charles Somerset† as governor of the Cape and criticized the Liverpool and Canning administrations for failing to resolve the matter promptly through inquiry, 17 May 1827.
The ministry counted Dalrymple among their ‘friends’ and he divided with them on the civil list when they were brought down, 15 Nov. 1830. He presented petitions from his constituents against slavery, 16 Nov., and for reform of parliamentary and municipal government, 6 Dec. 1830, 22 Feb., 19 Mar. 1831. He voted against the Grey ministry’s English reform bill at its second reading, 22 Mar., and for Gascoyne’s wrecking amendment, 19 Apr. Endorsing a hostile petition from Carlisle, 29 Mar., he objected strongly to the disfranchisement of 8-900 of its freemen and the ‘revolutionary character’ of the bill, which ‘deprived them of their hereditary rights’. The Lowthers briefly contemplated putting him up there as a second ‘Yellow’ at the ensuing general election.
Using his military expertise to assist the Conservative opposition, Dalrymple called repeatedly and ultimately successfully for an end to alleged abuses in the commutation of soldiers’ pensions, the assisted emigration scheme and provisions for officers’ widows, 17 Feb., 2, 4 Apr., 3 Aug. 1832. He also upheld the rights of foreign officers to half-pay and to hold civilian posts, 26 July. He could be relied on to defend the interests of the planters and colonial legislatures and, as he had already intimated to Fowell Buxton, when they met out riding earlier that day, he spoke in favour of the government amendment limiting the scope of his proposed inquiry into colonial slavery with a view to its abolition, 24 May.
At the general election of 1832 Dalrymple belatedly stood as a self-styled ‘Peelite Conservative’ for Brighton, where his regiment was based, and finished a poor fifth.
