Cammish emerged on top after a race-long battle with Jake Hill in wet conditions, and managed to work his Motorbase Performance Ford Focus ST past the West Surrey Racing BMW 330e M Sport of Hill on the 19th of what became 21 laps of racing.
Hill had emerged relatively unscathed from contact with the front-row-sitting Motorbase Fords off the grid at the start of the race.
While poleman Dan Rowbottom made a sluggish getaway, team-mate Ash Sutton was also prone to the fast-starting rear-wheel-drive BMW of Hill.
Hill was pincered between them, and slight contact with Rowbottom deflected him into Sutton, who was forced onto the grass on the approach to the first corner.
Colin Turkington snuck through to briefly make it a 1-2 for the WSR BMW team, but had the Fords of Rowbottom and Cammish gnashing at his rear bumper into the Old Hairpin and ran wide, dropping into the midfield.
The safety car emerged at the end of the opening lap due to Tom Chilton being parked off the track at Schwantz Curve, and Sutton, who was still running in the leading bunch, dived for the pits and retirement following his off.
Chilton managed to get going again so the safety car period was only brief, and at the restart Hill led Cammish and the Excelr8 Motorsport Hyundai i30 N of reigning champion Tom Ingram.
Source: Autosport