The temperature at Arbour Park was hovering around freezing point, but there was no doubt about the game going ahead, which gave the Rebels a real boost as they looked to close the gap on Leamington at the top of the league.
It was clear from early on, though, that Banbury would be looking to complete the double over Slough, and the visitors looked confident in possession and happy to pass the ball forward from the back.
The first half was largely even and ended goalless, perhaps shaded by the home side. Lewis Putman, playing out wide on the left, cut inside and sent a shot through to Harding, whilst Gunn headed a difficult chance off target.
Banbury built a promising attack with 11 minutes played when poor Slough defending presented the ball to Jack Self inside the Slough half. He found Conor McDonagh, who turned well but shot wastefully wide from 25 yards.
Harding twice almost got his team into trouble with poor distribution, but he redeemed himself second time round by turning behind another Putman strike.
Slough found their path to goal blocked when Putman played a nice ball in for Simon Dunn, but his attempted low cross was crucially cut out and both goalkeepers made it to half time without being troubled further.
Banbury started the second half in the ascendancy and McDonagh saw an effort deflected into the side netting by Lee Togwell. In response, Nathan Smart whipped in a cross which Elijah Adebayo rose well to meet, but his header drifted wide.
But on 55 minutes, the visitors had their best chance to take the lead. Mark Scott did well to rush out of his goal to block from Eddie Odhiambo, and the ball ran to Darius Browne who tried to beat the Slough defenders retreating back to the unguarded goal, but could only put his effort wide.
This prompted a positive spell for Banbury, who enjoyed a lot of ball possession without truly hurting the Rebels in key areas.
On 62 minutes, Slough changed things around with Charlie Moone replacing Adebayo, and the home side clicked into gear.
Paul Stonehouse almost immediately went close as he thundered a shot over the bar from the edge of the box, but just a minute later Slough took the lead.
Slough kept the pressure on the visitors after a corner was only cleared to Sean Fraser 30 yards out. The skipper hooked the ball back into the penalty area where Guy Hollis lost his marker and headed past Harding from six yards out.
Banbury remained in the game but still could not penetrate the Slough defence, and with three minutes left the home side made sure of the points.
Andy Gunn was shown the only caution of the game after felling Putman, who took the ball deep into the Banbury half on the break. James Dobson stepped up to strike the free kick and despite it not being his best effort of the season, the ball hit Marvin Martin in the defensive wall and looped into the top corner, wrong-footing Harding and giving him no chance.
Banbury United Line up
Jack Harding, Callum White, Marvin Martin, George Nash, Luke Carnell, Andy Gunn, Zac McEachran, Jack Self (George Jeacock 77), Conor McDonagh, Eddie Odhiambo (Jack Westbrook 58), Darius Browne (Sam Humphreys 73). Subs not used: Ricky Johnson, Mark Bell.