Alastair Seeley became the first rider not on a Honda to take a series win this season as he beat Joe Talbot by 1.467secs at a wet Brands Hatch.
As points leader and polesitter Dan Linfoot crashed out while running in sixth position on lap nine, Billy McConnell took third ahead of Richard Kerr, as Lewis Rollo rounded out the top five.
Pirelli National Superstock with Santander Consumer Finance, race one result:
1. Alastair Seeley (SYNETIQ BMW Motorrad)
2. Joe Talbot (JR Performance Racing) +1.467s
3. Billy McConnell (C&L Fairburn Properties Jackson Racing) +4.579s
4. Richard Kerr (AMD Motorsport) +25.081s
5. Lewis Rollo (IN Competition/Aprilia +27.963s