Fairford dominated possession in the opening stages of the premier division clash but Saints gradually eased themselves into the driving seat. Fairford went close when a long goal kick was headed on and hooked goal wards by Dan Bailey with Ali Worby beaten but his effort hit the bar.
Saints broke the deadlock moments later when a sweet move involving Gordon Kille and Ryan Knight saw George Ball head home at the far post.
Dan Gudger was denied by Worby and at the other end Ball cut inside and hit a shot which was tipped over the bar by Ben Mitchell. From the resulting corner, James Watts swung the ball in at speed and after a deflection off a defender Kille bundled the ball over the line.
Saints nearly added a third in first half stoppage-time when James Hammond broke into the box on the right and crossed back to Ryan Knight whose shot was hooked off the line.
The second half had barely started when a misplaced defensive header led to Gudger nipping in behind and accurately shooting past Worby to reduce the arrears.
Fairford were content to defend deep at catch Saints on the break. But Fairford did create a couple of moments of panic in the Saints defence not least of all when Curtis Green and Worby hesitated on the edge of the box, Gudger nipped between them and there were claims for a penalty as he collided with the keeper.
As Fairford began to tire Saints began to find space and create opportunities. Hammond shot over before he squared the ball for Knight whose shot was desperately cleared off the line again.
Worby was forced to tip over the bar as Saints held on to take three more points ahead of Tuesday’s trip to Windsor.