By 1762, he was an accomplished portrait artist, and his 1764 group portrait James Shuttleworth, his Wife and Daughter is acknowledged as his first true masterpiece.
Pada 1762, ia telah menjadi pelukis potret yang sempurna, dan lukisan potret kelompoknya berjudul James Shuttleworth, Istri dan Anaknya pada tahun 1764 dikenal sebagai mahakarya pertamanya.