Playing down the slope in the first half, Luke Lee gave Sumas the lead on the half-hour mark and Khalid Senussi then doubled the advantage.
Ardley halved the deficit soon after the interval but the visitors held on to record an impressive victory.
"All in all it was the best win of the season," Herridge told the News. "It wasn't the easiest of games, it was a 7.30 kick-off, the pitch was terrible after the rain and Ardley were in good form.
"But we came away from the cup game last week thinking we had every chance of beating them in the league.
"I have always had the belief that we are a good footballing side but to play on a pitch like that and to dig in and grind out a result was fantastic."
* SEE THIS WEEK'S NEWS FOR FULL INTERVIEW AND MORE WOKINGHAM & EMMBROOK NEWS