As an amateur, Gavin won a gold medal in the lightweight division at the 2007 World Championships, becoming England's first ever winner of that event.

Internationally, Gavin defeated Giovanni Frontin of Mauritius to win a gold at the 2006 Commonwealth Games in the lightweight (60 kg) division.

Frankie then caused a huge upset by defeating Russian superstar Aleksei Tishchenko, unbeaten in four years, to reach the final where he beat Italian Domenico Valentino 19:10.

He signed a contract with promoter Frank Warren and agreed to be trained by Anthony Farnell in Manchester.

He made his debut with Olympians James Degale and Billy Joe Saunders which he won with a 4th round stoppage.