From A Dictionary of Irish Artists 1913
Was son of Sir Michael Mitchell, merchant and alderman of Dublin, who was Sheriff of the city in 1683, Lord Mayor in 1691-3, M.P. in 1692, and died in 1699. His mother, Elizabeth Lady Mitchell, died in 1739. He practised portrait painting in Dublin; but although his artistic career extended over a period of at east forty years little is known of his works. The first mention of him occurs in 1711, when he painted a portrait of "Dean Drelincourt" for the Blue-coat School. The painter's receipt for twenty pounds for the picture and five pounds for the frame, dated 1st December, 1711, is preserved in the school; but this picture, which is mentioned in Whitelaw and Walsh's "History of Dublin" as hanging in the school in 1818, is no longer there. In a receipt for eighteen shillings and threepence paid to William Wilkinson in 1754 for cleaning and repairing the picture it is described as a whole-length.*
In 1718 Mitchell was commissioned by the Corporation of Dublin to repair the portrait of King George I in the Tholsel, which on the night of the 29th June was "maliciously defaced and cut in pieces" by "some infamous, wicked and disaffected persons" who broke into the Tholsel. A thousand pounds reward was offered by the Lords Justices, and four hundred by the Corporation for the discovery of the offenders. In 1722 he cleaned and varnished the portraits in the Mayor's Hall and repaired those of King William and Queen Mary, together with the drapery of King Charles II and Queen Anne (Corporation Records). In 1728 he painted for the city full-length portraits of George II and Queen Caroline, "in one frame like William and Mary are"; and in the same year he cleaned and repaired the pictures in the Tholsel. In 1736 Mitchell received twenty pounds from the Corporation on his petition setting forth that from declension in business in his profession he had laboured under great difficulties in supporting his numerous family, and in 1738 he was paid fifteen pounds for painting portraits of King George II and Queen Caroline, which were hung in the Mayor's Hall, and for cleaning and repairing pictures and frames.
A portrait of "Griselda Steevens," painted by Mitchell in 1741, hangs in Steevens' Hospital where his receipt, dated 25th July, 1741, for £11 16s. 6d., is preserved. A portrait of "Thomas Wyndham," Lord Chancellor of Ireland, by him was engraved in mezzotint by Thomas Beard in 1728.
Mitchell died on 23rd August, 1750, "much esteemed by all those who had the happiness of his acquaintance" ("Faulkner's Journal," 25th-28th Aug., 1750); and was buried the same day in the old churchyard of St. Patrick's.
NOTE: * Other pictures formerly in the Blue-coat School have also disappeared. The portraits of "George II" and "Queen Caroline" painted by Mitchell for the city, "William III," "Queen Mary," and "General Ginkell," were taken there from the Tholsel when that building was demolished in 1805 and hung in the school-room. Whitelaw and Walsh's "History of Dublin" describes them in 1818 as "in a wretched, filthy state of repair." The only pictures now in the School are a large full-length portrait of "King Charles II" hanging in the Dining Hall, the altar-piece by Waldron (q.v.), and the portrait group by Trotter (q.v.) in the Board-room.