He was educated at Christ's Hospital, from 1770 until 1777, when he was apprenticed to a jeweller and watchmaker, whose daughter, Elizabeth Cousen, he married on 2 November 1785 at St James's, Westminster.
[2] Dagley wrote art criticism for the Literary Gazette,[3] and published his first book, Gems Selected from the Antique, in 1804, with plates he had drawn and engraved himself.
He produced some humorous illustrations for Isaac D'Israeli's Flim-Flams (1805) and a poem called Takings by Thomas Gaspey (1821), for which he wrote an introductory essay entitled 'Miscellaneous Observations on the Ludicrous in Art'.
In a preface he noted:... nearly twenty years since, while selecting and drawing from the casts of antique gems, for a publication that has since appeared, I was called upon to, make designs for the "Flim-Flams," a work of an entirely opposite character.
[7] Dagley died of influenza at his home, 5 Earl's Court Terrace, London, on 1 April 1841, and was buried at St Mary Abbots, Kensingtons.