The No.10 was in excellent form with the boot and in the final analysis was the difference between the two sides as he slotted five penalties and three conversions to underpin the victory.
Grayson opened his side’s account after just five minutes, following a high-tackle by Bristol flanker Matt Salter on Steve Williams but the lead was shortlived with his opposite number Felipe Contepomi scoring a try in the right-hand corner as he followed up a break by Jamie Williams.
With Contepomi adding the conversion and then kicking a further three points, Bristol took an early initiative but Grayson kept chipping away at the scoreboard, kicking his third penalty when Shoguns hooker was sent to the sin-bin.
Northampton’s Mattie Stewart was the next man to receive a yellow card and Bristol made their extra man count, skipper and second row Garath Archer completing a simple catch-and-drive at a lineout.
But Bristol could not hold onto their lead with Grayson kicking a fourth penalty and then centre John Leslie scoring Northampton’s first try.
After the break, Saints increased their lead through a Budge Pountney try, Grayson again on target with the kick at goal and despite Bristol matching their opponents try-for-try, were able to cruise through for a well-deserved victory.
So, more disappointment for Bristol who, despite remaining competitive throughout the contest, were again to slump to their third successive defeat this season.
For Bristol Shoguns: Tries: Garath Archer, Felipe Contepomi, Brendon Daniel Cons: Felipe Contepomi (2) Pens: Felipe Contepomi (3)
For Northampton Saints Tries: Ben Cohen, John Leslie, Budge Pountney Cons: Paul Grayson (3) Pens: Paul Grayson (5)