The 24-year-old eventually finished nearly 4.5s ahead of Morgan and has now moved into third place in the points, just 17 off table-topper Tom Ingram (Speedworks Toyota).
“We certain made the right choice on tyres,” said Sutton. “I went to the grid on wet tyres and only then fitted the slicks, and so I didn’t have as much temperature as those around me.
“But we played it well and I managed to get the grip quite quickly. What a race and the guys in the team have played a huge role in this so thanks to them.”
Third place fell to Ingram after a sensational drive through the pack. He had started from 27th place after a fly-by-wire throttle problem in the opening race, but picked his way through the field and claimed third when Senna Proctor’s Power Maxed Racing Vauxhall slid wide at the final chicane on lap 17.
Proctor held on fto fourth place, ahead of Colin Turkington’s WSR BMW and Chris Smiley’s BTC Norlin Honda.
Mike Bushell’s Team Hard VW had run in third place early on, but dropped back down the order to seventh position, ahead of Rory Butcher’s AmDTuning MG, Matt Simpson’s Eurotech Honda and Tom Chilton’s Motorbase Ford, which has been drawn on pole for race three.