[1] Thornhill also held the Lonsdale belt before being stripped after failing a drugs test.

He boxed for Higherside A.B.C,[3] St Helens Star A.B.C, then Transport A.B.C where he met his trainer, George Vaughan, who carried his career through to the paid ranks when Thornhill turned 24.

Thornhill turned professional in February 1993 at the Epic Leisure Centre, Ellesmere Port, Cheshire, England.

In his debut Thornhill defeated Sheffield's Brian Hickey with a fourth round knockout.

At super-featherweight Thornhill was central area champion, WBO Intercontinental champion, and he also went on to win a British featherweight title fight with a 9th round stoppage against fellow Liverpudlian Richie Wenton in May 2000, but was stripped of the title after testing positive for amphetamines after the fight and banned for six months.