‘Letter to the Prince of Wales on the subject of the Debts contracted by him since 1787.’ This went through thirteen editions. Lord Thurlow moved in the House of Lords for the disclosure of the author's name. Unable thenceforth to obtain employment from Pitt, Miles retired to Froyle in Hampshire. In 1796, in a ‘Letter to H. Duncombe, Esq., Member for the County of York,’ he answered Burke's ‘Letter to a Noble Lord,’ the pamphlet reaching a fourth edition within the year.
Miles returned to London early in 1800, but in 1803 retired to a house lent him by his friend Charles Sturt on Brownsea (now called Branksea) Island in Poole Harbour. On the death of Pitt in 1806 he sought employment from the new ministry, and was promised the consul-generalship at Corfu, but the death of Fox prevented the fulfilment of the promise. He now busied himself in writing for the press. In the ‘Independent Whig’ appeared his ‘Letters of Neptune’ on parliamentary reform. He also wrote in favour of Burdett's candidature for Westminster in 1807, and contributed to the ‘Statesman.’ In July Miles obtained through Lord Moira an interview with the Prince of Wales, and in the following year published his ‘Letter to the Prince of Wales, with a Sketch of the Prospect before him,’ London, 1808, Appendix and notes. It was answered by William Pettmann [q. v.], writing under the pseudonym ‘Philopolites.’ In 1812 he removed to Hythe, near Southampton, and corresponded with Whitbread, Lord Moira, and other public men. 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. He died at Paris on 25 April 1817. Lafayette attended his funeral.
Among Miles's numerous friends, besides those already mentioned, were Horne Tooke, Sir Alexander Ball, Sir John Warren, Andrew Saunders, and Lord Rodney; and he corresponded at different times with Goldsmith, Somers-Cocks, and Pye, the Poet Laureate. His ‘Authentic Correspondence with Lebrun,’ London, 1796, supplies much valuable information. To Lebrun as to Latude, the celebrated prisoner of the Bastille, he rendered pecuniary assistance. The Letters of ‘Neptune’ gave Thackeray some hints in the composition of his ‘Four Georges,’ and his ‘Correspondence on the French Revolution, 1789–1817,’ edited by his son Charles Popham Miles [see below] in 1890, is of considerable historical value. In addition to the pamphlets already noticed, Miles published: 1. ‘Remarks on an Act of Parliament passed in Fifteenth Year of his Majesty's Reign, intituled “An Act for the Encouragement of the Fisheries carried on from Great Britain,”’ London, 1779. 2. ‘Cursory Reflections on Public Men and Public Measures’ (written at Aschaffenburg in 1789, and translated by Lebrun). 3. ‘On the Expediency and Justice of Prescribing Bounds to the Russian Empire,’ 1791, in which a Suez canal was suggested (see art. in Times, 16 Nov. 1855); a copy is in the Imperial Library, St. Petersburg. 4. ‘The Conduct of France towards Great Britain Examined.’ Appendix and notes, 1793. 5. ‘Letter to the Earl of Wycombe on the Present State of Ireland,’ London, 1804. He was also the author of two comic operas: ‘Summer Amusements, or an Adventure at Margate,’ written in conjunction with Miles Peter Andrews [q. v.], and produced at the Haymarket in 1779 with music by Arnold, and ‘The Artifice,’ in two acts, London, 1780 (dedicated to Sheridan).
He married his first wife in 1772; she died in 1792, leaving a daughter Theodosia (b. 1773). In 1803 Miles married Harriet Watkinson of Bristol, who died at Monkwearmouth in 1872. By her he had five sons, of whom three entered the army; Robert Henry (lieutenant-colonel) accompanied M. de Lesseps upon his tour of inspection before the opening of the Suez Canal for traffic, and died at Malta in 1867; Frederick Alexander, translated into Oordoo Pinnock's ‘Catechism of Astronomy,’ commanded a battery in the Punjaub campaign, 1848–9, and died soon after his return to England; and Rawdon Muir (captain) was killed in the retreat from Cabul in January 1842. The youngest son, Thomas Willoughby, was drowned in his boyhood.
The fourth son, Charles Popham Miles (1810–1891), divine, after attending Morpeth grammar school and serving in the East India Company's navy as a midshipman, graduated at Caius College, Cambridge, B.A. in 1838, M.A. in 1851, was ordained, in May 1838 became chaplain of the Sailors' Home, Wells Street, London Docks, held several curacies, and in 1843 succeeded Robert Montgomery as incumbent of St. Jude's, Glasgow; after a controversy in 1844 between him and his bishop (Russell of Glasgow), which led to a debate in the House of Lords (Hansard, 3rd ser. cv. 782–840), his benefice was withdrawn from episcopal jurisdiction. While at Glasgow Miles graduated M.D. From 1858 to 1867 he was principal of the Malta Protestant College, and from 1867 to 1883 rector of Monkwearmouth, where he restored the old Saxon church, and laboured with much success. In 1872 he was made hon. canon of Durham. He died when on a visit to Great
