Sam Olver's penalty before the break and an Alex Wootton try after looked to have rewarded a dominant second half, but the hosts came up with the deciding score just five minutes from time.
The Cherry and Whites had failed to make the most of a first half they edged and in which they produced the game's first try just 10 minutes in through Will Goodrick-Clark.
In muddy conditions, play was predictably forward orientated and when Gloucester's over-eagerness to turnover ball conceded a kickable penalty, Sam Olver got the Saints tally moving with a penalty.
With the home side having missed out on a similar chance just six minutes later, the Saints came out for the second half looking like a completely different team, despite having the wind in their faces.
Straight from the kick Danny Hobbs forced himself through Gloucester defenders and powered dangerously close to the whitewash.
It was just the start they needed and some five minutes into the second 40, George Wacokecoke's kick forward and gather took the Saints within touching distance again. This time the ball was recycled effectively and shipped to the safe hands of Alex Wootton who finished off an impressive and deserved try.
The Saints' pressure continued to build with each attack and Gloucester were left hanging on by the skin of their teeth, Olver just off the mark with a penalty and a pair of yellow cards reducing the hosts to just 13 men.
The infringements proved worthy sacrifice, however, as Gloucester held out and were thankful for another frustrating miss from the usually deadeye Olver.
The Saints pack had also been agonisingly held up over the line and Gloucester added insult to that injury by finding a lineout drive of their own and crashing into the lead.
Conversion missed, the Saints still knew that any shot at goal would be enough to steal back the points but in a game low on chances, their chance had gone and a tie that had looked particularly difficult on paper had proved just that.
10mins GLOS Try Goodrick-Clark 5-0
15mins SAINTS Pen Olver 5-3
21mins GLOS Miss pen
HALF-TIME GLOS 5 SAINTS 3
45mins SAINTS Try Wootton 5-8
55mins SAINTS Miss pen Olver
58mins GLOS Yellow Hill
60mins GLOS Yellow Safe
68mins SAINTS Miss pen Olver
74mins GLOS Try 10-8
FULL-TIME GLOS 10 SAINTS 8