He was a patriot and strong sympathiser with the cause of United Ireland in 1798, but in that year removed for professional reasons to Whitehaven in England with his wife and family.
Murphy had considerable practice as a miniature-painter, and was in that capacity attached to the household of Princess Charlotte, being in 1810 appointed painter in ordinary to Her Royal Highness.
The set were, however, purchased by a friend, Sir Gerard Noel, and it was suggested that use should be made of them by having them engraved as a series, with illustrative text from the pen of Murphy's daughter, Mrs. Anna Brownell Jameson.
Murphy occasionally exhibited miniatures in enamel or on ivory at the Royal Academy from 1800 to 1827, but his work did not attain any great distinction.
[2] Murphy died in March 1842, leaving by his wife, who survived him, five daughters, of whom the eldest, Anna Brownell, married Robert Jameson, and was the well-known writer on art.