Commentator, coach and former world champion Terry Griffiths looks back on 40 years of World Snooker in Sheffield. Griffiths won the World Snooker Championship in 1979 at one of the earliest tournaments at the Crucible. He is coach to 2017 semi-finalists Barry Hawkins and Ding Junhui. Sheffield Live reporter Azz Mohammed spoke with Terry Griffiths about how the game has changed.