Alastair Seeley took control as the Supersport pack hit the track for the first time this weekend at Cadwell Park, setting the pace on a wet track.
The Binch Pro Yamaha rider clocked a best lap of 1min 43.144secs to lead to go 0.200secs clear of Rhys Irwin.
Third quickest was Honda Racing UK’s Dean Harrison, followed by Asher Durham as Jack Kennedy rounded out the top five.
Cameron Hall was quickest of the Cup riders, as he led Ben Tolliday and Lynden Leatherland.
And it was Jack Nixon who set the pace in the FP3 class, leading his Kramer Racing team-mate Owen Jenner with Lucca Allen third.
Quattro Group British Supersport & GP2/HEL Supersport Cup, FP1:
1. Alastair Seeley (Binch Pro Yamaha) 1min 43.144s
2. Rhys Irwin (Gearlink Kawasaki) +0.200s
3. Dean Harrison (Honda Racing UK) +0.203s
4. Asher Durham (Momentum G&S Racing Kawasaki) +1.067s
5. Jack Kennedy (Honda Racing UK) +1.415s