In an end-to-end first half at the Rivermoor on Saturday, City’s main threat came from Ollie Harris, who forced a smart save from the keeper before firing another effort just wide of the post.
City made a bright start to the second half with Ben Holder and Danny Williamson putting Wallingford on the back foot.
But when the visitors broke away, it needed a brilliant save by Charlie York to keep the game goalless.
That changed on the hour mark, however, when James Williams broke the deadlock, and then Williams set up the second goal for Adam Smith to double the lead in the 79th minute.
“It was a tight game, and I always thought the team that scored first would go on to win,” said City manager Simon Johnson.
“Once they were two up, they tried to do everything to slow the game down, and it was tough for us to get into any momentum.
“We had gone into the game on the back of two brilliant results and two clean sheets, but today we just came unstuck. But credit to Wallingford, they showed quality at important moments.
“From what I’ve seen in this league so far, it looks like any team can beat another on the day.”
The Cityzens face a particularly tough game this coming Saturday when they visit North Greenford United, who are unbeaten at Berkeley Fields with four wins and a draw.
They will be without Lewis Hayden, who is on a three-match suspension after his red card in the win at Bedfont on September 15.
* Woodley United were beaten 2-1 by Deportivo Galicia at Bedfont in the Esoteric Recordings Division One Cup on Tuesday. They trailed by two goals at half-time with Sam Garofalo pulling one back in the 55th minute.
United will be looking to end their run of five Division 1 games without a win when they host Belstone at Rivermoor Stadium on Saturday.
It looks a tough assignment for United, as Belstone sit sixth in the table with eight wins and three draws from 14 games. While they are unbeaten at home, their away form is patchy, with two wins, two draws and three defeats; they scored only six goals and conceded eight.
In their last two home games, they defeated Maidenhead Town 6-1 with Kushon Lewis-Thomas scoring a hat-trick, and then St Margaretsbury 6-1 in the Hertfordshire Senior Centenary Trophy.