In 1814 Peacock published a satirical ballad, "Sir Proteus", which appeared under the pseudonym "P. M. O'Donovan, Esq." Shelley resorted to him during the agitation of mind which preceded his separation from Harriet. After Shelley deserted Harriet, Peacock became an almost daily visitor throughout the winter of 1814–15 of Shelley and Mary Godwin (later Mary Shelley), at their London lodgings. In 1815 Peacock shared their voyage to the source of the Thames. "He seems", writes Charles Clairmont, Mary Godwin's stepbrother and a member of the party, "an idly-inclined man; indeed, he is professedly so in the summer; he owns he cannot apply himself to study, and thinks it more beneficial to him as a human being entirely to devote himself to the beauties of the season while they last; he was only happy while out from morning till night". By September 1815 when Shelley had taken up residence at Bishopsgate, near Windsor, Peacock had settled at Great Marlow. Peacock wrote "Headlong Hall" in 1815, and it was published the following year. With this work Peacock found the true field for his literary gift in the satiric novel, interspersed with delightful lyrics, amorous, narrative, or convivial.