Three tries in the first half had taken Saints 13 points in front. But the second half proved to be heavier going as Wasps battled hard to get back into the context. But with Martin Roberts diving over from close range a packed Gardens rose to celebrate as their team increased their lead over the league's chasing pack.
Results elsewhere in Round 18 had meant that at the start of play the Saints had slipped out of the top four. But while the hosts made all the early running, looking to put the ball through the hands at every opportunity in the opening exchanges, all of the action was in the home half. This was in no small part due to play breaking down at the crucial moment, and in those first 15 minutes more often than not a promising half-break would be followed by a fumble or stray pass.
Wasps were certainly giving as good as they were getting, taking the lead through a Nicky Robinson penalty and having a Hugo Southwell try chalked off after the full back strayed a couple of feet in front of Elliot Daly's pass while cutting a great line past the outside centre.
Southwell was leading by example, and he and Robinson used their left feet intelligently to pin Saints back in their territory repeatedly. Wasps were also getting parity at the scrum, and it was one such set piece which led to Robinson's opening three.
Ryan Lamb had missed an opportunity to equalise straight after the kick off, but he typified Saints' attitude when Robinson's next shot at the sticks fell well short.
The fly half sparked an attack which took Saints over halfway, and while a pass drifted into touch the hosts were in a position from which they would strike in some style.
Dominic Waldouck had been injured while chasing Robinson's kick, and with the centre lying prone and receiving treatment on the Saints' goal line referee Tim Wigglesworth waved play on, despite Ben Broster's best efforts to stop the clock.
James Craig pinched the lineout, and with Southwell coming into the line to cover Waldouck's absence there was acres of space to exploit. George Pisi did exactly that, sliding through a perfectly weighted grubber kick which sat up perfectly for Ben Foden to collect and touch down.
Lamb converted, but Wasps would not lie down and with Robinson landing his next two shots at the sticks the visitors were back in front. But when James Downey carved through the defence to dot down untouched, and Lamb added three points with his first penalty, Saints finally had a lead they would not relinquish.
The coup de grace to an ultimately dominant first half performance came five minutes before the break. Like his first try, Foden's second came from turnover ball. Richard Birkett was the culprit, spilling the ball in contact. Paul Diggin collected, spotted a potential overlap on the far side and although Wasps tried to cover they were ultimately powerless to stop Foden, Dickson and Chris Ashton interplaying to put the full back over in the right corner.
It was a fine score, but rather than kicking on in the second half Saints found themselves getting bogged down in an altogether scrappier affair.
Robinson and Lamb exchanged penalties, scores which sandwiched a pair of yellow cards shown to Broster and Andy Long for a bout of fisticuffs in the visitors' 22. But while they had been flowing in the first half, Saints just could not impose themselves in a similar manner, and as the game wore on the Gardens became noticeably more anxious that the sought after fourth try would remain elusive.
This was not helped by a pair of driving mauls just past the hour mark. The first looked dangerous and forced Broster to pull it down to stop it powering forward. But the second saw Roger Wilson - in a rare mistake from the Aviva man of the match - be ruled to have obstructed the defender and Wasps were able to clear.
But in the last 10 minutes Saints ratcheted up the pressure once again, Robinson saw yellow for kicking the ball away in frustration, and Roberts made the most of the extra space to nip over from a five-metre scrum to add the gloss his team, and their fans, wanted.
REFEREE Tim WIGGLESWORTH
TIMELINE
12mins WASPS Pen Robinson 0-3
13mins SAINTS Miss pen Lamb
16mins WASPS Miss pen Robinson
17mins SAINTS Try Foden Con Lamb 7-3
21mins WASPS Pen Robinson 7-6
25mins WASPS Pen Robinson 7-9
29mins SAINTS Try Downey 12-9
34mins SAINTS Pen Lamb 15-9
36mins SAINTS Try Foden Con Lamb 22-9
HALF-TIME SAINTS 22 WASPS 9
43mins WASPS Miss DG Robinson
44mins WASPS Pen Robinson 22-12
50mins WASPS Yellow card Broster
50mins SAINTS Yellow card Long
50mins SAINTS Miss pen Lamb
54mins SAINTS Pen Lamb 25-12
59mins WASPS Pen Robinson 25-15
74mins SAINTS Try Roberts Con Myler 32-15
FULL-TIME SAINTS 32 WASPS 15
