After retiring from the game in 2001, Thorne did not play for 16 years; however, he returned to action in 2017 in the World Seniors Championship, where he lost 1–3 in the first round to Aiden Owens. The World Seniors Tour was formed in the same year, but Thorne did not enter any events that season. He began his comeback in 2019 at the Seniors Irish Masters, where he faced Jimmy White in his first match in the quarter-finals, losing 0–3, and the World Seniors Championship, where he lost by the same scoreline in the first round to Darren Morgan. His next match, in the first round of the 2019 UK Seniors Championship, proved to be his last; drawn against Michael Judge, Thorne lost 2–3.