Goals from Jade Cross, Kelly Darby, Anna Morphet and Jamila Palmer saw Wolves run out convincing 4-1 winners in the match, which took place at the home of Kings Langley FC yesterday.
McNamara’s side have seen their last two league campaigns curtailed by the coronavirus pandemic.
But they are due to apply for promotion from level four and showed what they may be capable of in the division above after thrashing third-tier Watford.
“We are all absolutely ecstatic,” McNamara said. “The win has put us on top of the world but it didn’t come as a surprise.
“I think this is what you get when you have a group with real heart and desire and who are unified. That tells tells you everything you need to know about this team.
“The girls were amazing. They controlled the game and were good value for their win.
“They have had so many moments taken away from them in recent years.
“They thoroughly deserve this and their place in the fourth round.”