Harry Truelove kept Jack Kennedy at bay to take the Sprint race win at Cadwell Park by almost three seconds.
The Appleyard Macadam Racing rider took victory some 2.931secs clear of the championship leader at the end of a 12-lap scrap as GP2 runner Jack Scott came home third.
Truelove’s team-mate Bradley Perie was the fourth rider across the line before a 12 second gap to fifth-placed Eugene McManus.
Cameron Fraser was the second GP2 finisher in 13th spot overall, five seconds clear of Barry Burrell who was third of the GP2 runners in 14th.
Quattro Group British Supersport & British GP2 Championship, Cadwell Park, Sprint Race:
1. Harry Truelove (Appleyard Macadam Racing)
2. Jack Kennedy (Mar-Train Racing) +2.931s
3. Jack Scott (One-Kovara Projects/RS Racing) +3.586s
4. Bradley Perie (Appleyard Macadam Racing) +4.125s
5. Eugene McManus (Completely Motorbikes/Affinity) +16.317s