Thorburn last qualified for the World Championship in 1994, where he faced Nigel Bond in the first round. Thorburn led by 9–2 but eventually lost 9–10. He retired from the professional tournament circuit after the 1995–96 snooker season. In 2001, he won the pro-am Canadian Amateur Championship; he had previously won the tournament in 1974, 1975, 1976, and 1977.