The qualifying sessions were wet, which had caused the team problems.
"We had a messy qualifying which kind of ruined our Saturday as we were pretty quick for the majority of the session but we got messed up when the track dried. So the first race was pretty difficult for us. In this second race though I managed to stay in the lead and after the first couple of laps, Emil and Nick started fighting a bit so I got a bit of gap. I settled into a pretty good rhythm and was comfortable with what the car was doing.
Silverstone is a pretty cool place to get a win, first and second here great for the team's home race. I'm really happy," he said after the race.
Championship leader Lynn finished sixth after Eriksson tangled with Patric Niederhauser and Pal Varhaug and crashed out.
Ritchie Stanaway during the weekend's GP3 race at Silverstone
The result comes as the talented 22-year old makes a comeback to single-seater racing and the win propels him ever closer to the championship lead. Stanaway is still third in the series but has closed to within 20 points of Alex Lynn.
It has been a weekend of top results for New Zealand drivers: Auckland driver and 2012 GP3 champion Mitch Evans won his first GP2 feature race and also took top points at Silverstone, leaping to fourth overall in the championship, which is a feeder category to Formula One.
Meanwhile at home, a rising wave of New Zealand racing stars is embarking on the next phase in their careers.
Jamie Conroy of Invercargill has topped the annual New Zealand Motorsport Academy and is drawing together support for a proposed campaign in the 2015 Toyota Racing Series. Formula Ford national champion Conroy impressed when he drove the current FT40 TRS single-seaters at the annual post-championship test day in May. The drive was part of his championship prize package and was presented by Toyota New Zealand Motorsport Manager Steve Boyce.
At Manfeild this weekend (July 12 and 13) the fastest secondary school kart racers will contest KartSport New Zealand's National Schools' Championship. Backed by Toyota Racing New Zealand and held for the first time at KartSport Manawatu's circuit, the event is expected to attract 120 or more budding race drivers.