Frank Callan is the father of modern coaching, "one of a very select band of people who have insight into Snooker technique at the highest level," according to Steve Davis.
By analysing the mechanics of technique in an entirely fresh way, he challenged traditional methods of coaching and became the first man to whom professionals turned for help.
He first achieved widespread recognition in 1988 when Doug Mountjoy, having sunk to 24th in the rankings, came to him in despair.
Callan overhauled his technique, taught him new habits and in November that year, Mountjoy regained the UK title ten years after winning his first.
'Without that guy, I’m nothing," he said gratefully.
Callan also worked extensively with Terry Griffiths who became a disciple of his methods when he himself became a coach.
Frank Callan's Snooker Clinic, in our judgement the best Snooker coaching book ever written, is out of print but its essentials are timeless and we are therefore running them as a series for Snooker Scene website visitors.
Terry Griffiths won the English Amateur Championship in 1977 and 1978 before turning professional.
In his first season, he won the World Championship, the only player to do so on his debut at the Crucible Theatre.
Griffiths went on to win the 1982 UK Championship, beating Alex Higgins 16-15 in the final.
He had beaten Higgins 9-5 to win the Masters at Wembley in 1980 and captured three successive Irish Masters titles from 1980 to 1982.
Like everyone else in the 1980s, he competed in the shadow of Steve Davis, who won all seven of their meetings at the Crucible.
Among these was an 18-11 defeat in the 1988 final. Griffiths went on to reach the semi-finals at Sheffield in 1992 at the age of 44 but lost to Stephen Hendry, who won all 17 of their professional meetings.
His highest world ranking was third and he spent 17 successive seasons in the top 16 before being relegated from that elite in 1996.
He elected to retire rather than attempt to scrap through the qualifiers but on entering the World Championship one final time in 1997, reached the Crucible where he led his fellow Welshman Mark Williams 9-7 before losing 10-9.
Griffiths played 999 frames there. Of his 49 matches, he won 31 and reached the quarter-finals or better for nine successive years from 1984.
Three times Welsh Professional champion, Griffiths also captured the 1982 Lada Classic, 1986 Belgian Classic and earned £1,390,077 on the table.
