In the autumn of 1798, partly on account of his health, he determined to return to England with his daughter. The Elector of Bavaria, to show his esteem for Rumford, appointed him Minister Plenipotentiary and Envoy Extraordinary to the Court of St. James. On September 14, 1798, Lord Grenville sent a despatch to the Hon. Arthur Paget at Munich, saying, ‘It is, I apprehend, a thing if not wholly unprecedented, at least extremely unusual, to appoint a subject of the country to reside at the Court of his natural sovereign in the character of minister from a foreign prince. I am to direct you in the last resort to state in distinct terms that his Majesty will by no means consent to receive Count Rumford in the character which has been assigned to him. You will observe that the circumstance of Count Rumford having heretofore filled a confidential situation (that of Under-Secretary of State in the American Department) under his Majesty’s Government, makes the appointment in his person peculiarly improper and objectionable.’ On Count Rumford’s arrival on September 19 he wrote to Lord Grenville to say that, notwithstanding the information and the intimation which had been communicated to him by Mr. Canning, Under-Secretary of State for Foreign Affairs, he considered it his duty formally to notify that, having been appointed Envoy Extraordinary and Minister Plenipotentiary, he had come to England in consequence of that appointment, and was charged with a letter to the King, which he ought to endeavour to obtain permission to deliver with his own hands. He therefore asked an audience or personal interview with the minister, to state the objects of his mission, and to receive such information as would enable him to give a clear, authentic, and satisfactory account to the sovereign who had entrusted him with the management of his affairs. The day but one after, Lord Grenville shortly answers that ‘he conceives it will be more agreeable to Count Rumford that the substance of the representation with which Mr. Paget was charged should be transmitted by Count Rumford to the Elector rather than through any other channel.’ The same day a despatch to this effect was written to the Hon. Arthur Paget at Munich. No other notice was taken of Count Rumford’s appointment. He did not return to Munich, and the following year his master, the Elector Charles Theodore, died. The thoughts of Rumford, when rejected as minister of Bavaria, were directed to his native land. He thus wrote to his friend Baldwin in America: London, September 28, 1798.