His grandfather was a man of ability, an enterprising merchant of London, one of the commissioners of customs under the Tory ministry during the last four years of Queen Anne, and, in the judgment of Lord Bolingbroke, as deeply versed in the " commerce and finances of England " as any man of his time.
Queen Caroline was provoked into classing him and Bolingbroke, as "the two most worthless men of parts in the country."
The Walpoles, Bubb Dodington, Bolingbroke, Congreve, Sarah, duchess of Marlborough, Pope, were among his English friends.
A posthumous work entitled Contemplatio Philosophica was printed for private circulation in 1793 by his grandson, Sir William Young, Bart., prefaced by a life of the author, and with an appendix containing letters addressed to him by Bolingbroke, Bossuet, &c. Several short papers by him were published in Phil.
In August St John, who had on the 7th of July been created Viscount Bolingbroke and Baron St John of Lydiard Tregoze, went to France to conduct negotiations, and signed an armistice between England and France for four months on the 19th.