The 1977 World Snooker Championship was the first to be held at the Crucible Theatre. Thorburn became the first Canadian world snooker championship finalist. He whitewashed Chris Ross 11–0 in qualifying, then recorded a 13–6 win over Williams. In the quarter-final, he won in the deciding frame, 13–12, against Charlton. He overcame Taylor 18–16 in the semi-final, and twelve hours later was facing Spencer in the final. Spencer built a 4–2 lead at the end of the first , but Thorburn won four of the next six frames and they finished the second session level at 6–6. Thorburn took the first two frames of the third session, and it finished with them level again, at 9–9. Thorburn built a 13–11 lead during the fourth session, and extended it to 15–11 before Spencer won four consecutive frames to make it 15–15; the next session again saw them share the frames, finishing at 18–18. Spencer won three frames in a row to lead 21–18, with Thorburn taking the next two, to trail by just a single frame. Spencer took the last frame of the session, leading 22–20. In the last session, Thorburn again narrowed the gap to one frame, but then Spencer won three in a row to achieve victory at 25–21.