St. Clair, a professional soldier commissioned at the age of six, represented his native district of burghs as an Argyll and Walpole Whig, until turned out by the Squadrone in 1734. Having secured another seat on the interest of his kinsman, William, 17th Earl of Sutherland, he ‘made it his constant practice to support his Majesty’s measures’ throughout successive Administrations.
The General ... though rigorous in exacting obedience ... has insinuation and address to gain the sea officers and colonies. All our captains were exceedingly taken with his civilities.
On the cancellation of the American venture, the force made an unsuccessful attack on the French coast at L’Orient, St. Clair’s conduct of which was strongly criticized.
Defeated at Sutherland in 1747, St. Clair was obliged to return to Dysart Burghs, which he had intended for his nephew, Sir Harry Erskine, as part of a scheme concerted with his friend James Oswald to gain control of the county and boroughs of Fife.
In 1749 St. Clair, through Argyll, secured the return of Sir Harry Erskine, who in 1751 attacked General Philip Anstruther. Having by this incurred the hostility of the Duke of Cumberland, St. Clair in 1752 was refused the colonelcy of the 3rd Guards, which was given to Lord Rothes, Anstruther’s supporter in Fifeshire politics.
Our affairs in the county stand extremely well, Major Moncrieff’s attempt being laughed at by all the free-holders except those depending on the Anstruthers ... though joined by the party of the Earls of Rothes and Leven and supported by the War Office.
On being informed through Oswald that Pelham would give the government interest to Anstruther, St. Clair wrote a protest, which he asked Oswald to convey to Pelham ‘in the genteelest manner’ possible:
’Tis not from the vote against the gate of Edinburgh that this attack has taken its rise; ’tis from the General’s behaviour towards us ... to render both me and my nephew his implacable enemies ... He sent his agents to insinuate that as we were descended from Jacobite families we must be looked on as disaffected to his Majesty and his Government ... I never could have imagined my adversary’s military services could have weighed more with his Majesty than mine; I did not know his parliamentary services were greater. I doubt ... if Mr. Pelham will find his personal attachment to him is so great or so sincere ... it must not be supposed that after Mr. Anstruther’s insolent, outrageous and injurious behaviour he shall be suffered to tread me and my relations underfoot with impunity. I have given the strongest assurances to our friends in the Eastern [Anstruther] burghs that I never will abandon them ... Were I to desist, I should give the world reason to believe that I acquiesce in the aspersions spread by his emissaries.
Oswald mss; St. Clair to Oswald, 26 Jan. 1754, Mems. of Jas. Oswald, 330 et seq.
Returned for the county as a government supporter, attached to Argyll, he retained his seat till his death, 30 Nov. 1762.