Born in Glasgow, Reilly made his professional debut in October 1968.
In April that year he stopped defending holder Brian Hudson to take the BBBofC Southern Area title, leading to a British title eliminator against Jim Watt in September.
[1] Watt won that fight via a seventh round stoppage to earn the right to challenge for Ken Buchanan's British title.
Reilly opened a cut over Watt's right eyebrow in the seventh round and after the cut worsened the fight was stopped in the tenth, leaving Reilly the new British champion.
[2][3][4] Reilly's final fight was in March 1972, beating Herbie McLean on points at the Kelvin Hall in Glasgow.