To the party of this celebrated politician the Earl of Mar attached himself, with a tenacity for which those who recollected the hereditary politics of the Erskine family, could find no motives but self-interest. James, Duke of Queensbury, was, it is true, the son of one of the most active partisans of the Stuart family, to whom the house of Queensbury owed both its ducal rank and princely fortune. Possessed of good abilities, but devoid of application, and with the disadvantage to a public man of being of an easy, indolent temper, this celebrated promoter of the union between Scotland and England, had acquired, by courtesy, and by a long administration of affairs, a singular influence over his countrymen. His character has been written with a pen that could scarcely find sufficient invectives for those politicians who, in the opinion of the writer, were the ruin of their country. The Duke of Queensbury falls under the heaviest censures. "To outward appearance," says Lockhart, "he was of a gentle and good disposition, but inwardly a very devil, standing at nothing to advance his own interest and designs. Though his hypocrisy and dissimulation served him very much, yet he became so well known, that no man, except such as were his nearest friends, and _socii criminis_, gave him any trust; and so little regard had he to his promises and vows, that it was observed and notorious, that if he was at any pains to convince you of his friendship, and by swearing and imprecating curses on himself and family to assure you of his sincerity, then, to be sure, he was doing you underhand all the mischief in his power."[17]