1980 world snooker champion Thorburn had defeated Virgo 6–1 in the round robin phase of the
1980 Bombay International, but lost 7–13 to him in the final. He won 5–3 against Virgo in the first round of the
1980 Masters, then lost 3–5 to Griffiths in the quarter-final. In advance of the
1980 World Championship, he practiced at a club near the Crucible that was owned by a friend, and gave up smoking and drinking alcohol for a week before the tournament. His first match was against Mountjoy, Thorburn finishing their first session behind 3–5. In the evening, he played cards and drank alcohol with friends until 5:00am, resuming the match the next day by winning the first five frames in succession. Thorburn won the match 13–10. In the quarter-final, he beat
Jim Wych 13–6, having led 5–3, and 10–6. He led
David Taylor 5–3 after their first semi-final session, and 11–4 at the end of the second. In the last session of the match, Thorburn extended his lead to 15–7 by the mid-session interval, then won 16–7 with a break of 114 in the 23rd frame, becoming the first player to reach a second final at the Crucible. His opponent in the final was Higgins, the
1972 champion. Thorburn won the first frame, and Higgins won the next five. Thorburn won the seventh to make it 5–2, Higgins complaining after the frame that Thorburn had been standing in his line of sight, a claim that author and sports statistician Ian Morrison called "unfounded". Higgins led 6–3 at the end of the first session, extending this to 9–5 before Thorburn levelled the match at 9–9. Writing in
The Times, Sydney Friskin described the match to this point as a contrast of styles: "the shrewd cumulative processes of Thorburn against the explosive break-building of Higgins". He also noted that each player had accused the other of distracting them during the match. Thorburn won the 19th and 20th frames, Higgins taking the following two to level at 11–11. Thorburn went ahead at 12–11 and 13–12, Higgins levelling the match both times, and the third session ending 13–13. In the final session, Higgins won the first frame then Thorburn won the next two, before Higgins equalized at 15–15. Thorburn led 16–15, and missed an easy that let Higgins in to make it 16–16. With a break of 119, Thorburn moved within a frame of victory at 17–16. In the 34th frame, leading 45–9 in points, he laid a for Higgins, and made a 51 break after that to win the title. The
BBC's television coverage of the final had been interrupted by the broadcast of live footage of the
Iranian Embassy Siege. The conclusion of the final was watched by 14.5million television viewers. Thorburn is generally regarded as the first player from outside the United Kingdom to win the world championship,
Horace Lindrum's victory in the
1952 World Snooker Championship usually being disregarded. After the match, Higgins said of Thorburn "he's a grinder", and the nickname "The Grinder" was subsequently associated with Thorburn, seen as apt for his slow, determined style of play. Thorburn has aspired to be known by the nickname "Champagne Cliff", but admitted later that it never caught on. He won the Canadian Open for a third successive year in
1980, defeating Griffiths 17–10 in the final, and was part of the Canada Team that reached the final of the
1980 World Challenge Cup, where they lost 5–8 to Wales. He led Higgins 5–1 in the semi-final of the
1981 Masters, but lost the match 5–6. At the
1981 World Championship, as defending champion, he reached the semi-final where he lost 10–16 to
Steve Davis. Following a 4–10 loss to
Jimmy White in the first round of the
1982 World Snooker Championship, Thorburn decided to return to Canada. Thorburn had been number two in the
1980/1981 world rankings, and reached number one in the
1981/1982 rankings. He won the
1983 Masters, recovering from 2–5 against Charlton to win 6–5 in the semi-final, and defeating
Ray Reardon 9–7 in the final.
1983 world championship maximum break In 1983, Thorburn became the first player to make a maximum break at the
World Championship, Thorburn started the break by a . While he was completing the break, play stopped on the tournament's second
table because his friend and fellow Canadian
Bill Werbeniuk wanted to watch. The match against Griffiths ended at 3:51am, Thorburn emerging as the winner, 13–12. He then defeated
Kirk Stevens 13–12 (from 10–12) in the quarter-final, and
Tony Knowles 16–15 (from 13–15) in the semi-final. During the semi-final, which finished at 12:45am, Thorburn learnt that his wife Barbara had suffered a
miscarriage on the day of his maximum break. He played Steve Davis in the final. From 2–2 after the first four frames, Davis won four in a row to leave Thorburn behind 2–6, extending this to 2–9 at the start of the second session, and 5–12 at the end of the first day. Davis wrapped up victory on the second day, at 18–6, this being the first final at the Crucible to be completed in only three sessions. Commenting on Thorburn's performance in the final, snooker historian
Clive Everton observed that the long matches he had played in reaching the final had "left him so drained... that he was able to offer only token resistance."
1984 to 1989 Thorburn enjoyed a resurgence in form during the
1984–85 season. He reached the final of the
Grand Prix, where he lost to Dennis Taylor 2–10. In the semi-final, Thorburn had defeated the reigning world champion Steve Davis 9–7. He also reached the final of the
Classic in January 1985, where he met Thorne, the latter winning five frames in a row to win 13–8 after the pair had been tied at 8–8. Thorburn was again runner-up in the
1986 Classic, this time losing to Jimmy White in the final 12–13. Thorburn fluked a pot on the in the deciding frame, to leave White requiring snookers to win. White potted the brown and , then laid a snooker on the . Thorburn failed to hit the pink, which gave White the points he needed, and White then potted the pink and black to win the title. He won further Masters titles by defeating Mountjoy 9–6 in
1985, and White 9–5 in
1986. He became the first player ever to retain the Masters title, and the first to win it three times. Thorburn experienced success in the Scottish Masters, an invitational event which opened the snooker season, in
1985 and
1986. He defeated Thorne 9–7 in the 1985 final, and Alex Higgins 9–8 the following year. He won the opening ranking event in the
1985–86 snooker calendar, the
Matchroom Trophy, where he beat Jimmy White in the final 12–10, having trailed 0–7. He was then runner-up in the corresponding event the following two seasons, 9–12 to
Neal Foulds in
1986, and 5–12 to Davis in
1987. In 1988 Thorburn was fined £10,000, had two ranking points deducted, and was banned for two ranking tournaments, by the World Professional Billiards and Snooker Association. The Association's disciplinary committee had decided that Thorburn had brought the sport into disrepute, as a drug test that he took at the
1988 British Open showed that he had "minute traces of cocaine in his urine sample". He compiled another maximum break in the
1989 Matchroom League, during a match against White. ==Later years==