Garthshore, whose mother died soon after his birth, was given every educational advantage by his father, an eminent London accoucheur and son of a Kirkcudbright manse. Dr Cyril Jackson, dean of Christ Church, wrote of him to Lord Auckland, 24 Apr. 1790, that his father’s liberality had enabled him to extend Garthshore’s education
beyond the common plan. To a constant residence at Oxford for seven years, during the terms, he has added the advantage of spending three summers abroad, a very good knowledge of French, which he speaks fluently, a little German, and a considerable degree of information on modern history—and I trust that your lordship will see that he has the habits and manners of the best company.
He was originally intended for diplomacy but in 1790, on Jackson’s recommendation, was engaged by the Duke of Buccleuch as tutor to his heir during his tour of northern Europe, ‘well qualified for such an employment by his agreeable manners and address, his improvement in useful knowledge, and the strict propriety of his behaviour’. Auckland reported from The Hague that Garthshore’s ‘modesty ... borders on reserve’, but concluded that he was ‘a very excellent character in every possible respect’ and that his only difficulty arose from his wish to be regarded ‘as the friend and not the governor’ of Lord Dalkeith.
On his return in 1792, Garthshore eschewed remuneration, being satisfied that Buccleuch would further his career. The duke recommended him to Henry Dundas, who in 1794 appointed him his private secretary at the War Office, though the Duke of Portland was also prepared to accommodate him at the Home Office. The salary of £200 or £300 a year was not Garthshore’s object; he wished to be launched on a public career. On 18 Oct. 1794 Dundas informed Buccleuch: ‘When I have anything worthy your knowing, I can without reserve confide in Garshore [sic] with whom I am much satisfied. He is anxious and attentive to do well and perfectly understands his place.’ Canning, a fellow Christ Church man, wrote of him soon afterwards that he was ‘now private secretary to Mr Dundas, and married to a great fortune ... He has a house in Manchester Square, and gave a very good dinner to-day.’
Garthshore hankered after more conspicuous employment. Dundas suggested that he should accompany Lord Cornwallis to India as private secretary. After an interview with the latter, he demurred, 10 Feb. 1797: he could not agree to go ‘at his own expense’ or ‘in no ostensible situation’. In May 1797, when Thomas Wallace was appointed to the Treasury board, he became discontented: not because he envied Wallace the place, but because he felt in danger of being ‘totally left behind’ not only by his contemporaries, but by his juniors, in the competition for public employment, in which his talents had scarcely been tested. On 5 July, dissatisfied with Dundas’s reaction he set off for Scotland, threatening to give up public life if Dundas could not improve on ‘the subordinate part in the office which has so long fallen to my lot’.
On 27 Jan. 1798 Garthshore applied to Dundas for other employment: his retirement had led to ‘impertinent not to say ill-natured conjectures’. When Dundas brushed him off with the implication that he had been amply rewarded for his services to Buccleuch and that his advantageous marriage had ensured him security, he became indignant: his circumstances had been as respectable before his marriage as after it and money had been at no time his object. All he sought was an official footing. Soon afterwards he had to deny hostility to Dundas. In 1799, after serving on the copper committee in the House in April, he was sent to Stockholm on official business, but was home by August: ‘little, or rather nothing was to be done there’. By then he was an habitué of Uxbridge House and a dining companion of the Prince of Wales. On 7 Jan. 1801 Buccleuch warned Dundas that Garthshore was a disappointed man and that they both had to answer for it.