Kyle McFarlane (pictured) fired Blues into the lead just after the half-hour mark with a well-struck effort from 20 yards out.
But the advantage lasted only a matter of minutes before the hosts levelled the scores.
With an hour played, QPR struck the decisive winning goal to claim all three points on the PDL 2 fixture.
The game also saw both sides miss a penalty.
Blues academy coach Steve Spooner admitted his side fell short of the standards they had set themselves in recent weeks.
“We didn’t play very well and that was probably the worst we’ve been with the ball in the last five or six weeks," he said.
“We lacked energy, tempo and pace and we didn’t play with the industry and determination that we have been playing with.”
He continued: “But looking at the positives we stayed with it and battled away.
“We also didn’t concede from a set play and QPR are a very dangerous side at set-plays because of their size.
“That was one of the objectives that we laid down before the game and we defended those well.”