Mahon 4.5.1803 at Joseph Johnson's
It would be surprising if this was Philip Henry Stanhope Hist of Parl 1781-1855 known till 1816 as Viscount Mahon, as although he was educated by Jeremiah Joyce, at this point he had been disinherited by his father, the radical peer Charles Stanhope, and appointed Lt Governor of Dover Castle by Pitt on £500 p.a. and Johnson's dinners had a radical reputation. Another Mahon was Gertrude Mahon DNB 1752-1808+ the "Bird of Paradise", she might have been welcome at Johnson's dinners as a rejected superstar like Mary Robinson, but it seems unlikely, and her husband Gilbreath Mahon had been a gambler and was maybe already dead. John, James and William Mahon can all be found in Highfill, Burnim & Langhans and were a family of musicians, especially clarinettists, they seem a better bet but still not typical Johnson dinner guests.