But the largely second-string Northampton team were pushed all the way by their Championship opponents, who possessed a number of Saints, past and present.
Tries from Sam Dickinson, Howard Packman, Vasily Artemyev, Tom Stephenson, George Wacocoke and Tom Collins, plus six points from the boot of Sam Olver and two from Harry Mallinder ensured the win.
Moseley, though, showed plenty of spirit and scored four tries of their own, with rapid wing Matthew Williams and No.8 Chris Brightwell the stand-out members of the home side.
For Saints it was a good squad work-out ahead of Friday night’s game against Edinburgh, which will include many of last season’s star names.
Moseley, who included former Northampton wing Scott Armstrong in their team, made Jim Mallinder’s men scrap for every ball from the off.
And the hosts were the first to get some points on the board as Caolan Ryan cooly slotted a penalty.
Saints’ fly-half Olver had the chance to level the scores at the other end, but he fired the ball wide of the posts.
It wasn’t too long before the away side got themselves on the board, though, as they cranked up the heat from the restart.
A spell of sustained pressure was eventually made to pay as former Rotherham forward Dickinson, who was skipper for the night, burst over the line to put Saints ahead.
Olver kept his composure to make the conversion from the right of the posts and his side held a 7-3 lead after a lively opening 10 minutes.
Moseley weren’t deterred, though, and after maintaining a steady set piece a quick break from Williams resulted in a try, converted by Ryan.
Saints soon silenced the home cheers as Dickinson again found himself in space, firing a pass out wide to Packman, who ate up the ground to score.
Olver missed a tricky kick from out wide and, in what was proving to be a see-saw encounter, Moseley soon regained the lead.
Williams, a wing with pace to burn, charged down the left, a la San Francisco speedster Carlin Isles at the recent World Club 7s tournament, and touched down behind the Saints posts.
But there was a worrying moment soon after as Moseley centre Anthony Carter was carried off on a spinal board after a collision that saw him attended to by both medical teams.
When the game restarted, Ryan slotted the conversion, but Saints soon edged ahead once more as Artemyev danced inside Armstrong to dot down.
Olver floated the conversion of beautifully from the left touchline and the away side held a two-point lead.
Saints turned to the pack to try to extend their advantage and a lineout drive pushed Moseley No.5 Mike Powell to the limit, forcing him to pick up a yellow.
The Moseley fans’ cries of ‘come on, ref, it’s only a friendly’ were ignored and Saints stepped up the pressure, being held up twice before centre Stephenson eventually scored.
Moseley set the early pace in the second half, with wing Williams so eager to get involved he stuck his head into a maul and helped earn a penalty.
But Ryan missed the kick and the home side also surendered a chance to score a try soon after as Simon Hunt’s late pass failed to find its target.
But Moseley didn’t have to wait too long for their third try of the night as the influential Brigthwell turned on the power to score.
The home fans were sensing an upset when Ryan brought their side within a point with a penalty, but their revival was ended by two late tries.
Junior academy wing Wacocoke side-stepped his way over and Collins grabbed a score in the 79th minute, with Mallinder making one conversion and hitting the post with the other.
Typically, Moseley kept pushing until the last and claimed a deserved late penalty try as their determined pack had too much for their young Saints counterparts.
Ryan kicked the points to put the seal on an entertaining night of rugby, which left a decent crowd in good spirits as they trudged out of Billesley Common.
Moseley: Penn; Armstrong, Owen, Carter, Williams; Ryan, Brown; Warren, W Evans, B Evans; Hill, Powell; Burrows, Robinson, Brightwell.
Replacements: Hilton, Randall, Parkins, Woolford, Carpenter, Brazier, Hunt, Browne, Dacres, Mason, Thomas, D Evans.
Saints: Artemyev (Collins 58); Skelcey, Diggin (Cooke 77), Stephenson (Mallinder 58), Packman; Olver (Wakocoke 69), A Day (Glynn 56); E Waller (Hobbs-Awoyemi 65), McMillan (Marshall 58), Herriott (E Waller 69); Craig (Onojaife 58), Verbakel (Peters 56); Harrison (Conner 74), Nutley (Harry 56), Dickinson (c).