Harold Thornton started work in a cotton mill, receiving training in evening classes at Burnley School of Art. In 1930 he won a scholarship to attend the Royal College of Art in London. In 1939, he returned to Burnley as Principal of the School of Art, having for the previous five years been assistant master at Plymouth School of Art.
In addition to painting in oils, Mr Thornton had a personal interest in sculpture. He also lead the students in developing experimental glazing of ceramics. In 1952, around 50 students attended the pottery classes. A Burnley Express article in 1953 includes three photographs of him working in the college pottery studio at Claremont School. (Burnley Express September 12, 1953 page 8).
Note there is another artist named Harold Thornton (1892-1958), a watercolourist who lived in London. This has led to some confusion as neither artist is listed in the Getty Union List of Artist Names (ULAN), see About Artists Entries.