Dings, trailing 17-16 deep into stoppage time, attempted to attack from deep inside their own 22.
But the move broke down and the turnover ball was gratefully received by replacement scrum-half Geraint Davies, who raced in under the posts, which gave Daniel Robson the easiest of conversions and deprived the home side of a much-needed bonus-point in their battle against relegation.
Dings player coach Sam Cox
, who was forced to miss the clash due to a hamstring injury, did his best to put on a brave face on the deflating defeat. He said: "It's obviously very disappointing to lose a game in such a manner. We dominated them in the scrums, and I thought our backs did everything we asked of them – they ran straight and hard, and gave our forwards targets to aim at.
"But we need to improve at the line-out and, perhaps, we could have worked harder when we didn't have the ball – especially our kick-chase game. I don't think we could ask the boys for more effort, but we have to learn to keep our focus for longer periods, and our game-management needs to improve in certain situations."
The home side began brightly and dominated the scrums, with front trio David Hilton, Dave Wheeler and the impressive Chas Meddick imposing their will from the start. But Dings' line-out spluttered throughout the contest and continues to be their Achilles heel. Hartpury, by contrast, were imperious at the line-out and looked dangerous every time they got the ball in the wide channels.
The home side made the first clean break, with centre Sheldon Stevens slicing through the Hartpury defence, only for the visitors to win the ensuing ruck and clear the danger.
Hartpury wing Russell Westcott opened the scoring with an unconverted try after 30 minutes, before Dings responded with two penalties from fly-half Mitch Burton. Dings continued to make inroads through their forwards, with No 8 Buster Lawrence, flanker Elliott Goodman and lock Ed Hack
in the thick of the action, while skipper Stean Williams
was, more often than not, the first to arrive at the breakdown.
The visitors regained the lead when flanker Alexander Woodburn broke through some flimsy defence to score a converted try just before half-time.
On 44 minutes, the students extended their lead when former Cleve lock Harry Casson showed power and pace to score an unconverted try out wide.
Dings' forward-power was rewarded after 56 minutes with a penalty try, converted by Burton, who also nudged over a penalty ten minutes later, to bring his team to within a point of the visitors.
But Dings' late error meant they had nothing to show for their efforts.