Born in London, Cantwell represented England in the light flyweight division at the 1990 Commonwealth Games in Auckland, New Zealand.
[3] Cantwell turned professional in 1991 and, unbeaten in his first seven fights, beat Darren Fifield in April 1993 to take the vacant BBBofC Southern Area flyweight title.
Five months later he challenged for Pablo Tiznado's WBC International light flyweight title, losing on points - his first professional defeat.
[8] Cantwell's final fight came in September 2001 when he unsuccessfully challenged Jacob Matlala for the WBU light flyweight title, the South African stopping him in the fifth round.
[10] After an incident in September 2008 in which Cantwell knocked his manager Alan Irwin out during an argument at the Trades Union Congress in Brighton, he was convicted of assault causing actual bodily harm and sentenced to 200 hours of unpaid work.