His older brother, Roy St. Clair, alongside Terry Downes, trained Tony, to follow in his father's footsteps.
During that reign, he would hold the (Mountevans Rules) World Heavyweight Championship between 1982 and 1984, winning from and losing back to Mighty John Quinn.
Along the way engaging in several inconclusive unification matches with Wayne Bridges who had won a vacant Joint Promotions splinter claim after Quinn's move to All Star in 1981 and later followed Quinn across to the rival promotion, confronting St. Clair in the ring before a match on S4C's Welsh language wrestling TV show Reslo in 1983.
St. Clair finally lost the British Heavyweight Championship to Kendo Nagasaki after reigning as champion for nearly a decade.
St Clair's British title claim had remained undisputed until 1985 when - three years after his departure - Joint Promotions, with recognition from ITV - set up an alternative version.
In 1989, there were plans to unify All Star Wrestling and Joint Promotions' British Heavyweight titles, pitting St. Clair against Dalbir Singh after the latter joined All Star Wrestling, but Singh renounced his claim to the title, making St. Clair the undisputed British Heavyweight Champion once again.
In November 1988, he and Croatian Mile Zrno defeated Fit Finlay and Mark Rocco to become the first CWA World Tag Team Champions.
In October 1992, St. Clair was awarded the CWA British Commonwealth Championship, before losing it that night to Jimmy Snuka.
In 2018 St Clair was inducted into the Hall of Fame at the British Wrestlers Reunion at The Bridges Public House in Kent.
St Clair was a special guest at Cheltenham Town Hall on February 19 for World Pro Wrestling at ALL-Star Extravaganza.