The fifth different winner in five races, Kirkham will also start the second race from pole position after scoring the fastest lap on the final revolution.
Byrne's retirement, meanwhile, means Hopkins is now leading the BSB standings by six points.
Mason completed his first podium result for MSS Colchester Kawasaki, a crucial result for the former BSB Cup winner having struggled to make an impression aboard the ZX-10R so far this year.
Loris Baz was a distant fourth, the Frenchman another to benefit from the safety car after an awful start from third on the grid left him as low as 17th position at one stage, while Lowes held on for an excellent fifth place finish and another EVO victory – his fourth from five races.
Stuart Easton completed a good race for Kawasaki in sixth position, ahead of Peter Hickman, scoring his best BSB finish in seventh, Josh Brookes in eighth, Glen Richards in ninth and Tommy Bridewell in tenth position.
Further back, Hudson Kennaugh scored Splitlath Aprilia's first points of the year in a fine 11th, ahead of James Westmoreland and Buildbase BMW duo John Laverty and Ian Lowry.
Hill, meanwhile, soldiered on to score a solitary point in 15th position, the Swan Yamaha rider faring better than Laverty, who pulled into the pit lane before returning to the circuit a lap down.
Having struggled for speed all weekend, Ryuichi Kiyonari endured a similarly dismal race, dropping from 14th to as low as 25th at one point before eventually pitting.