The following year, he painted an altarpiece for the Basilica of San Gregorio Magno al Celio, on the Caelian Hill.
Known as the Academy of English Professors of the Liberal Arts, it was in operation for only six years, when major disagreements among its members forced the Earl to order it closed.
[2] During its brief existence, it also provided copies of the Italian Old Masters for the English art market, and Parker worked as an agent.
[3] His best known student was the German artist, Franz Ignaz Oefele, who became a court painter in Munich.
In 1762, he returned to England and, the following year, participated in an exhibition at the Free Society of Artists, where he presented a self-portrait and an historical scene, depicting the assassination of David Rizzio.