Gardner’s second goal of the season came just two minutes after Loxwood thought they had sealed victory through Gary Pritchard’s deflected effort.
The United line-up showed one change to the side that confidently despatched Littlehampton Town the previous Saturday, with Adam Davidson returning to partner Dan Pollard at the heart of the defence in place of Peter Featherstone.
Loxwood, who are unbeaten at home in the league since 16th September, saw two early efforts fail to trouble United stopper Russ Tanner as Ollie Gill curled onto the top of the crossbar before Michael Wood fired high over when well placed six yards from goal.
Mark Cave saw an effort rebound off the post and into the arms of a grateful Tanner, before Wes Tate had United’s first effort of the game that was comfortably saved by Sam Smith.
Peter Cooper saw a deflected left footed effort gathered by Smith soon after before Tate hit the side netting following Cooper’s interception of a weak goal kick from Smith.
Chances came and went at either end of the pitch with neither ‘keeper being fully tested before United took the lead on 40 minutes.
A long ball from Tanner was flicked into the path of Tate, who remained composed and lifted the ball over Smith to score in a fourth consecutive Division One fixture.
The lead was short lived however, as two minutes later Cave thundered an unstoppable header past Tanner from an outswinging corner.
The second half saw the action go much the same as the first, as Cave and his replacement Tim Martin fire over, while Davidson and Tate warmed the gloves of Smith.
United were forced into a defensive reshuffle after Brad Lewis (hamstring) and Davidson (ankle) were withdrawn from the action and replaced by Gardner and Andy Corrigan.
Jason Taylor was denied by an acrobatic stop from Smith as full time approached, but as the clock neared 90 minutes, The Magpies looked to have stolen the three points when Pritchard’s goalbound effort was deflected in off Dean Stevens.
Smith again denied Taylor with a low stop as United searched for an equaliser, before in the 91st minute, Simon Rowland’s men were rewarded when Gardner reacted quickest to a loose ball in the area following a Tate corner and his goalbound effort managed to find a way past Smith and send United home with a share of the points.