The Honda Racing rider became the fifth different race winner of 2020 – after brother Andrew (Honda Racing), Tommy Bridewell (Oxford Products Racing), Christian Iddon (VisionTrack Ducati) and Josh Brookes (VisionTrack Ducati) – and holds a lead of 23 points over Bridewell, who finished +1.138 in arrears in second place.
Christian Iddon, third in the overall standings, finished third with Lee Jackson (Massingberd-Mundy Kawasaki) fourth, Josh Brookes, who won Race 2, in fifth and Tarran MacKenzie (McAMS Yamaha) completing the top six.
Irwin made decisive moves on lap nine and 10, first passing Iddon and then Bridewell, in the 16-lap race at the Norfolk circuit to secure his first win of the season at the sixth time of asking.
RACE TWO REPORT
Australian Josh Brookes won Round 5 of the British Superbike Championship at Snetterton ahead of championship leader Glenn Irwin.
Brookes and Irwin tussled in the opening lap before the latter took a lead heading into Riches.
Moments later and Danny Buchan crashed into Bradley Ray at Agostini to make for the Massingberd-Mundy Kawasaki rider's second race crash in a row.
Watch Josh Brookes storm to victory in BSB Round 5 at Snetterton
Brookes raced back into the lead in the third lap with him and Irwin would continuing to battle at the front. Irwin tried to take the lead at Agostini, but he ran wide to allow Brookes back in to first.
Brooks managed to hold off challenges from Irwin, Tommy Bridewell and Lee Jackson to seal the victory. Irwin finished second and Bridewell third.
'Woah!' - Danny Buchan furious as he crashes at Snetterton
RYDE TOOK WARM-UP TOP SPOT
Kyle Ryde topped Sunday morning's warm up session, waiting until his final lap to pip pacesetter Glenn Irwin and posted his fastest time which put the Buildbase Suzuki rider 0.202s in front ahead of rounds five and six.