The next year he moved into the Zealous with Captain (later Sir) Samuel Hood, and was present at the disastrous attack on Santa Cruz in July 1797, and at the battle of the Nile on 1–2 August 1798.
When he returned to England however Mitford found that the position did not exist and Bridget Perceval wanted him instead to join her campaign in support of Princess Caroline (a neighbour in Blackheath).
While Mitford was helping Bridget Perceval place letters in the newspapers he was hidden away in Warburton's private asylum in Hoxton, Whitmore House.
[2] Mitford's stay in Warburton's asylum provided him with the material for two anonymous pamphlets (published in the 1820s) exposing the exploitation, neglect and abuse of patients.
The same year saw the publication (under the pseudonym of Alfred Burton) of Mitford's most famous work: The adventures of Johnny Newcome in the navy, a poem in four cantos, illustrated by Thomas Rowlandson.
Mitford wrote the poem in six weeks whilst sleeping out in Bayswater Fields under a shelter made of nettles, and washing in a gravel pit.
[2] Mitford defended the reputation of Emma, Lady Hamilton when Edward Pelham Brenton, in his Naval history of Great Britain, accused her of having demanded to be rowed round the Minerva to see Admiral Caracciolo hanging.
[2] Mitford's unconventional life-style and association with publishers such as William Benbow and Edward Duncombe made him the subject of harsh criticism, although his talents as a writer were recognised.