1977, the championship moved to its new home at the Crucible Theatre in Sheffield, where it has remained ever since. The 1977 championship featured sixteen competitors: eight seeded players and eight qualifiers. John Spencer beat defending champion Ray Reardon 13–6 in the quarter-finals, and met Canadian Cliff Thorburn in the final. The two players were closely matched throughout, the score being tied at 9–9 after the first day and 18–18 after the second. Spencer led 22–20 after the first session on the final day, and pulled ahead to win 25–21 in the final session of the match. Defending champion John Spencer lost to Perrie Mans in the first round of the 1978 championship. The 1977 runner-up Cliff Thorburn was defeated 12–13 in his quarter-final match against Eddie Charlton, who won the last five frames. However, Charlton then lost to Ray Reardon in the semi-finals; he was ahead 12–9 after the first three sessions of the match, but Reardon won all seven frames of the fourth session to win 18–14. Mans met sixty-four-year-old Fred Davis in the other semi-final, defeating him 18–16. Reardon won the final 25–18 to claim his sixth world title. He became the oldest World Champion, aged . The first seven World Snooker Champions all won a championship when in their forties; the last of these was Reardon. It would be another forty years before a quadragenarian won the title again, as Mark Williams won the 2018 championship aged forty-three. The 1979 championship was won by Terry Griffiths who had only turned professional seven months prior to the tournament, and needed to win two qualifying matches to reach the Crucible. Griffiths was trailing 16–17 against Eddie Charlton in the semi-final, before eventually winning the match 19–17 at 1.40 am. He then beat Dennis Taylor 24–16 in the final, winning the record first prize of £10,000. Canadian Bill Werbeniuk made a break of 142 in his quarter-final match against John Virgo, equalling the championship record set by Rex Williams in South Africa in 1965. In the 1980 championship, the number of participants was extended to twenty-four players. Those seeded from nine to sixteen each met a qualifier in the first round, the winner meeting one of the top eight seeds in the second round. Several changes were made to accommodate the extra matches, including a reduction in the number of frames played in the final, to a maximum of