John-Henry Keet, 14, won a points verdict after three rounds against Liam Dunne (Odyssey Boxing Club, Ashford, Middlesex) in the Junior Southern Counties Under-62kg category final in Brighton.
Keet now travels to Bristol to face local boxer Teo Miles (Barton Hill BC) in the national quarter-finals.
Another victory would take him to Newcastle the following weekend, where the national semi-final and final are due to be staged on successive days.
Keet is trained by Leigh Park head coach Rob Ford, and Bessey said: ‘We’re all really excited about John-Henry’s win - it’s a big thing for a club like ours.
‘Everyone’s buzzing about it.’