Returning multiple champion Jack Kennedy topped the first free practice timesheets as the series hit Oulton Park for the first time, beating Eugene McManus by 0.840secs.
In split sessions, the opening group featuring Kennedy and McManus proved to be the fastest, as Alastair Seeley ended the session third quickest, with a best lap of 1min 46.282s.
Fourth quickest was Shane Richardson, with defending champion Ben Currie fifth.
The GP2 riders had a strong session, with Jack Nixon leading the way on the Kramer with the sixth best lap overall, ahead of Lucca Allen and Maximus Hardy
Quattro Group British Supersport and GP2 Cup, FP1 combined.
1. Jack Kennedy (Honda Racing UK) 1min 45.151s
2. Eugene McManus (ROKit Haslam Racing Ducati)
3. Alastair Seeley (Binch Pro Yamaha) 1min 46.282s
4. Shane Richardson (Astro-JJR Hippo Suzuki) 1min 46.608
5. Ben Currie (Oxford Products Racing Ducati) 1min 48.610s