[1] Born 1 July 1753 or 1754, he was son of Jefferson Miles, who was employed as proof-master general (died 1763), a supervisory artillery position.
Miles's position in the Low Countries placed him as a crossroads for intelligence, and also enabled contacts with French officials.
[4] The events leading to the creation of the Republic of Liège saw Miles move to Brussels: he made a vain attempt in 1789 to persuade Pitt to interfere in those affairs.
On 5 March 1790 he had an interview with Pitt, and in July was sent to Paris with a view to inducing the National Constituent Assembly to annul the third Pacte de Famille with Spain.
Pitt offered him a pension for his past services, and he acted as intermediary between the agents of the French republic in London and the ministry, seeking to prevent war.
[2] Miles returned to London early in 1800, but in 1803 retired to a house lent him by his friend Charles Sturt on Brownsea Island in Poole Harbour.
On 23 April 1816 he started for Paris, in order to collect materials for a history of the French Revolution, and stayed a month at Chateau Lagrange with Lafayette.
[2] In Paris Miles came to know Mirabeau, Henri Lebrun, Lafayette (whom he had met in America), and other leading politicians.
Among his numerous friends were Horne Tooke, Sir Alexander Ball, Sir John Warren, Andrew Saunders, and Lord Rodney; and he corresponded at different times with Oliver Goldsmith, John Somers Cocks, and Henry James Pye.
[2] Miles was also the author of two comic operas: Summer Amusements, or an Adventure at Margate, written with Miles Peter Andrews, and produced at the Haymarket Theatre in 1779, with music by Arnold; and The Artifice, in two acts, London, 1780, dedicated to Richard Brinsley Sheridan.