 Thornhill claimed his first national silverware when Cork defeated Tipperary by 8-09 to 6-04 to win the 1939-40 National League title.He was again at full-back when Cork surrendered their provincial title to Limerick in the 1940 Munster final.After winning a second successive National League medal after a 4-11 to 2-07 victory over Dublin in the 1941 league final, Thornhill lined out in the second All-Ireland final of his career on 28 September 1941 when he was selected at full-back against Dublin.