The negotiation was begun at Prior's house, where the queen's ministers met Mesnager, September 20,1711, and entered privately upon the great business. The importance of Prior appears from the mention made of him by St. John in his letter to the queen. "My lord treasurer moved, and all my lords were of the same opinion, that Mr. Prior should be added to those who are empowered to sign; the reason for which is, because he, having personally treated with monsieur de Torcy, is the best witness we can produce of the sense in which the general preliminary engagements are entered into: besides which, as he is the best versed in matters of trade of all your majesty's servants who have been trusted in this secret, if you shall think fit to employ him in the future treaty of commerce, it will be of consequence that he has been a party concerned in concluding that convention, which must be the rule of this treaty." The assembly of this important night was, in some degree, clandestine, the design of treating not being yet openly declared, and, when the whigs returned to power, was aggravated to a charge of high treason; though, as Prior remarks in his imperfect answer to the report of the committee of secrecy, no treaty ever was made without private interviews and preliminary discussions. My business is not the history of the peace, but the life of Prior. The conferences began at Utrecht on the 1st of January, 1711-12, and the English plenipotentiaries arrived on the 15th. The ministers of the different potentates conferred and conferred; but the peace advanced so slowly that speedier methods were found necessary; and Bolingbroke was sent to Paris to adjust differences with less formality; Prior either accompanied him or followed him, and, after his departure, had the appointments and authority of an ambassador, though no publick character. By some mistake of the queen's orders, the court of France had been disgusted; and Bolingbroke says in his letter, "Dear Mat, hide the nakedness of thy country, and give the best turn thy fertile brain will furnish thee with to the blunders of thy countrymen, who are not much better politicians than the French are poets." Soon after, the duke of Shrewsbury went on a formal embassy to Paris. It is related by Boyer, that the intention was to have joined Prior in the same commission, but that Shrewsbury refused to be associated with a man so meanly born. Prior, therefore, continued to act without a title, till the duke returned, next year, to England, and then he assumed the style and dignity of ambassador.