Stuart joined the navy and served in the Mediterranean, the Channel and the West Indies.1R. D. Rees ‘Parl. Rep. S. Wales 1790-1830’ (Reading Univ. Ph.D. thesis, 1962), ii. 531; J. Wilson, Biog. Index (1808), 119. Returned on the family interest for the Glamorgan boroughs in 1802, he can seldom have attended, but was on affable terms with his constituents during his rare visits to Cardiff for elections.2Cambrian, 8 Nov. 1806, 2 May 1807. Like his father, a sympathizer with Lord Grenville after 1801, Stuart opposed Addington’s conduct of the war against France and on 23 Apr. 1804 voted for Fox’s defence motion. He had written from Sheerness to Pitt on 15 Apr. offering to prove to him, on the basis of nine months’ cruising ‘during the present war’, how ‘inefficient and inadequate the present Admiralty are to hold the responsible and important situations they do’. This was intended to help Pitt if he again brought forward ‘an inquiry into the naval defence of this country’, and Stuart offered him his vote.3PRO 30/8/181, f. 164. Pitt’s friends seem to have been a little uncertain of him, for they listed him ‘Prince’ in May 1804 and ‘Fox and Grenville’ in September, before altering him to ‘Pitt’ with the comment ‘deduct from opposition’. In July 1805 he was definitely ‘Pitt’.
His father supported the Grenville ministry and went into opposition with them, and in 1810 the Whigs listed Stuart as one of their adherents; but he was evidently unable to attend to vote with them, if that was his intention. They listed him among absent friends on Morpeth’s Irish censure motion, 4 Feb. 1812, and once (6 May 1812) he appeared in the minority list, against delays in Chancery. On 8 Apr. 1812 the House was informed that he was to be court-martialled for running on shore the Conquistador. He is not known to have spoken in the House. Before the election of 1812, Tierney tried to get his seat for Francis Horner by pressure on Lord Bute, as Lord William was ‘always at sea’. Nothing came of this, and after the election George Rose described him as ‘friendly notwithstanding his father’s politics’.4Grey mss, Tierney to Grey, 26 Sept.; T.64/261, Rose to ?Arbuthnot, 8 Nov. 1812. Stuart was duly listed ‘Government’ by the Treasury, though he was listed as an absent friend of Catholic relief, 24 May 1813. He died at sea, 25 July 1814, on his passage from Jamaica.5Gent. Mag. (1814), ii. 400.