Richard Cooper was back on the top step of the podium for the second time in as many hours after destroying the opposition to take the Sprint win.
Aboard the Russell Racing Yamaha, Cooper was running second on lap two when championship leader Tom Booth-Amos retired.
Hitting the front, Cooper put his head down and quickly built up a solid lead to eventually win by 5.135secs.
Ben Currie was second – and went back to the top of the points standings as a result – while a delighted Zak Corderoy celebrated his first class podium in third.
Rhys Irwin was fourth and off the podium for the first time in a while, as Eugene McManus was fifth on the Completely Motorbikes Triumph to make it five different manufacturers in the top five.
Over in GP2, Harry Rowlings took his first class win this season as he finished 12th overall, with Joe Collier second and Cameron Fraser third.
Quattro Group British Supersport and British GP2 Championship, Sprint result:
1. Richard Cooper (Russell Racing)
2. Ben Currie (Oxford Products Racing Ducati) +5.135s
3. Zak Corderoy (Gearlink Kawasaki) +5.936s
4. Rhys Irwin (Astro-JJR Suzuki) +8.836s
5. Eugene McManus (Completely Motorbikes Triumph) +12.063s