Maitland, a professional soldier, was returned on the interest of his elder brother for Haddington Burghs in 1790, after a contest. He referred in his maiden speech, 28 Feb. 1791, to his 16 years’ ‘hard service’ in India, which was the pretext for a somewhat rambling exposé of the dangers of over expansion there through warring with the native princes. While India and his profession remained his pet subjects in debate, he was launched, on 12 Apr. 1791, in his subsidiary role as opposition seconder, which together with frequent duty as teller devolved on him as brother of one of the Whig grandees, when he supported Grey’s motion against the Russian armament. On 10 May, as predicted, he voted for the exemption of Scotland from the Test Act. On 3 May he was admitted to the Whig Club and on 6 June to Brooks’s. After a visit to Paris with his brother later that year,
Maitland, whose signature followed Grey’s in the roll of the Association of the Friends of the People, vindicated the Friends in the House in defence of parliamentary reform on 30 Apr. and 25 May 1792 and resisted enticements to desert. He was also a Friend of the Liberty of the Press.
In 1795 he several times questioned the conduct of the war by ministers and continued to vote against it until June, after which he was sent to San Domingo and experienced débâcles at first hand both there and subsequently in the expedition to Belle Ile in 1800. He acquitted Sir James Pulteney of blame in the failure to take Ferrol and Sir James unsuccessfully applied to the Duke of York to have Maitland appointed his quartermaster general. Maitland began to chafe at being passed over for promotion, and was too proud to volunteer service under any other officer: to his friend William Huskisson he wrote from Lisbon, 17 Nov. 1800:
The lowness of my rank in the army precludes me from looking forward to it as an object of any fair ultimate ambition ... On the other hand the line I adopted in politics originally and that which my friends still adhere to preclude me from having any chance of advancing myself out of my profession.
He concluded by offering to be employed anywhere, under Henry Dundas’s auspices, but he was disappointed.
On returning home Maitland resumed his seat for the family burghs, which was vacated for him by the sitting Member, March 1802. He soon rallied to Addington’s pacific ministry: although he had privately described the peace treaty to Fox as ‘a mere truce’, in debate he hailed it diplomatically as ‘as honourable as could be made, and as likely to be permanent as any peace that had ever been concluded before’, 14 March 1802. On the same theme, 24 Nov., he insisted on the adequacy of the military establishment and deprecated any renewal of hostilities. Fox described this speech as ‘very good’, apart from ‘a little imprudence at the end of it’, and regarded Maitland as a potential go-between for himself with Addington. On 8 Dec. Maitland announced his concurrence in government policy and was reported as having spoken ‘as a man enlisted’.
From February to April 1804 Maitland was often government teller and a prominent defender of Addington’s defence arrangements against their critics, not least against Pitt. The return to power of the latter sent him into the wilderness. There seem to have been hopes of detaching him from opposition, despite his marked hostility to Pitt’s additional force bill, 18 June 1804. He was awarded the government of Ceylon that winter and persuaded his brother to concur in his seat being occupied by a friend of the ministry.
It was as a colonial governor that ‘King Tom’ came into his own and he was philosophic about his brother’s failure to obtain high office in 1806: ‘the whole of it’, he explained to Huskisson ‘is only one additional proof to me that all of us when embarked in political contest are guided by little else but the immediate rein of self interest’. He remained in Ceylon until 1811. On his recall, which he evidently disliked, he was ‘perhaps worth £25,000 clear’, but handicapped by the discount on Ceylon paper currency when liquidating his debts. He wanted employment on the Staff at home, according to the Duke of York’s secretary Gordon, who described him as ‘a very clever man, but he inclines to be prosy’. He resumed his seat at the election of 1812, when he was also nominally a candidate for Stirling Burghs. He was an advocate of stern measures against seditious persons in Yorkshire late in 1812, earning the commendation of the Home secretary. He is reported as having voted against Catholic relief, 2 Mar. 1813, but for the relief bill on 13 and 24 May. Soon afterwards, disillusioned with politics, and ‘not liking to quarrel with Lauderdale and yet neither liking his friends Grey or Grenville’, he accepted the government of Malta and, after the conclusion of peace, added to it the administration of the Ionian isles. He died, a benevolent despot, in Malta, 17 Jan. 1824.
