Eliot, his father’s favourite, was returned by him for St. Germans when his elder brother Edward James, to whom he was deeply attached, vacated the seat soon after the election of 1790 to sit for the other family borough of Liskeard: he himself later transferred to that borough. He was intended for a diplomatic career and went abroad in the summer of 1791. While serving his apprenticeship at Berlin in October 1791 he was recommended by Lord Grenville to succeed to the post of secretary of the legation. His superior Joseph Ewart commended his ‘sound judgment and capacity’. The minister, Sir Morton Eden, found him ‘perfectly accommodating, but too silent’ in the post, so he informed Grenville. Eliot followed up this situation with an assignment at The Hague, one which his father, writing to Pitt, described as ‘very near my heart’.
In January 1795, while at home, Eliot was found ‘a proper person’ to receive the exiled princesses of Orange at Yarmouth. A year later he declined going to Constantinople, but was sent to Germany, returning home in 1798. Before his marriage the previous year, although his mother-in-law thought him ‘very entertaining and agreeable’, his father-in-law, Lord Stafford, had expressed doubts as to Eliot’s financial security, which he had brushed aside by reference to the non-political tendency of diplomatic posts and to collateral expectations. Late in 1799 Stafford, still anxious, asked Pitt to make Eliot a groom of the bedchamber. Pitt began to cast about for a suitable place for him and in July 1800 secured him a place on the Admiralty board: Lord Granville Leveson Gower had waived it in favour of the next vacancy at the Treasury board and Lord Temple had declined it. Pitt arranged this, he informed the King, ‘as he is on many accounts very anxious for some situation at home and as his obtaining it will be highly gratifying both to Lord Stafford and to Lord Eliot’.
Eliot wished to resign with Pitt in February 1801, but was dissuaded, ‘to prevent the coming in of a Jacobin administration’. He thereby held on to £1,000 p.a. In the winter of 1802-
that whenever Mr Pitt opposes the present administration I think in all probability I shall be guided in my vote by his opinion. I wish him to resume his situation of first minister of this country, and will give the little assistance I may be of to the measures which he himself may bring forward or approve towards that end, but to no others. You will now judge how far such opinions are consistent with the place I hold.
He had written to Pitt on 14 Nov., ‘Whenever I distinctly understand that your object is to remove the present administration my insignificant weight will be immediately taken out of their balance’. St. Vincent complained to Addington, 25 Dec., ‘his object has been to hold his office and to evade Parliament. I have told him ... that I cannot possibly be a party to his absence from the duties of the office for a longer period than the latter end of next month.’ Addington informed Eliot that his conduct was unreasonable, 27 Dec., and four days later he penned his resignation.3 He went on to vote with Pitt and Fox on the defence motions of 23 and 25 Apr. 1804 that brought down Addington.
He was under-secretary to Lord Harrowby at the Foreign Office in Pitt’s second administration. In December 1804 he and his family went down with scarlet fever, and early in 1805 he resigned his place, wanted by Lord Mulgrave for Robert Ward, when his father-in-law fell out with Pitt. When he was restored to health he again supported Pitt, voting against the censure of Melville, 8 Apr. 1805, and in July was mentioned by Canning as a likely secretary of the Treasury, if his wife’s health permitted.