The Manse Lane outfit headed into the game having won just one of their previous nine in the league and in serious need of a result to get their season back on track.
Lewis Stephens got them off to a fine start, registering his first goal for the club since his transfer from Tadcaster Albion with just 10 minutes on the clock and the hosts continued to create chances throughout the opening period.
But, they failed to convert any of them and were pegged back just six minutes after the resumption when Stephen Crawford struck for Campion.
Ewan Gregson then missed a 71st-minute penalty and the visitors headed straight down the other end and took the lead through Aidan Kirby.
And although Stephens nodded in a Gregson corner on 79 minutes to earn Boro a share of the spoils, Parkes was still left frustrated at the final whistle.
"I think you probably go into the game against the team that is top of league thinking that you would be fairly happy to walk away with a draw, particularly with the way things have been going for us recently,” he told the Harrogate Advertiser.
“But, after the way that the first 45 minutes went, I really think that we should have come away with all three points.
“We could quite easily have come in 3-0 up, we missed some great chances, a couple of one-on-ones, and we should have been awarded a penalty for what was a clear and obvious handball.
“Campion then made it 1-1 shortly after half-time and we then missed a penalty before they went down the other end and scored to make it 2-1.
“We were hurting at that point. We should have been winning the game but instead found ourselves behind, and to be fair, the lads showed real character to recover from that.
"To bounce back from that position against the league leaders, I’ve got to be fairly happy, but when I look back I’m still disappointed with the result. We should have won.”
Saturday’s result lifts Knaresborough one place to 10th position in the NCEL Premier Division standings.