Scots fail to press their case as Jackson falls to injury and Pisi's quick-fire double

Northampton 24 Glasgow 15

Ken Pisi of Northampton makes a break with the ball (Getty Images)

Scottish rugby needed a serious performance from Glasgow yesterday, for political reasons as much as sporting ones. What it received was a performance of the curate's egg variety: outstandingly good for 30 minutes, not so hot for the other 50. Gregor Townsend's side may yet challenge for a place in the knock-out stage – victory over Ulster, last season's runners-up, at Scotstoun on Friday night will put them back in the mix – but by slipping off their game as they did here they merely reinforced the English in their view that the Cup's format is crying out for change.

The Premiership clubs, not least Northampton, have long believed that guaranteed places for the two Scottish professional sides is the very opposite of meritocratic. Put bluntly, they believe those from north of the Roman wall have had a free ride in Europe for far too long. As Edinburgh had done little to disabuse them of that notion by shipping 45 unanswered points to Saracens on Saturday, it was down to Glasgow to fly the flag. This they did, for half an hour – not nearly long enough.

In that time they opened up a 15-point lead over a startled band of Midlanders who had started the game as hot favourites with their captain Dylan Hartley's swift return to fitness – the England hooker was in the thick of it a mere fortnight after suffering a fractured eye socket – and nursing Courtney Lawes back to something like his best form following long-term injury. If Lawes made the earth move early on with his tackling, not least on John Barclay as the Test flanker sought the game's opening try, the impacts made by the visiting backs Sean Lamont and Ruaridh Jackson were significantly greater.

Even though Glasgow lost their counter-attacking full-back Stuart Hogg to injury inside 10 minutes, they ran Northampton ragged. Jackson looked like a thoroughbred No 10, playing flat to the line and mixing up his passing game sufficiently cleverly to wrong-foot the home midfield defence, while Lamont was effective at both ends of the pitch.

First Lamont made a try-saving tackle on Ken Pisi, who went hard for the corner after a surge from Lawes' locking partner Samu Manoa, to protect Glasgow's initial three-point lead. Then when he stampeded into the hosts' 22 from Al Kellock's line-out delivery, the impressively hirsute South African flanker Josh Strauss was on hand to score from close in.

Lamont was at it again on 28 minutes, completing another move straight from a line-out by finishing strongly in the left corner. But shortly afterwards, Jackson was hit hard in a tackle and needed lengthy treatment on a mangled hip bone: while he tried to continue, his lack of mobility weakened the Glasgow barricades.

As a result, the second of the Pisi brothers, centre George, claimed two tries in four minutes to turn the contest on its head: the first from a lucky ricochet off Tommy Seymour, the second following the sweetest of slice-through runs from his sibling, roaming adventurously off the wing.

The Scots were bitterly frustrated by the leaking of soft points. "We put our heart and soul into the game and gave it everything we had, physically and mentally, so to play such fantastic stuff for half an hour and then let them back in by making errors is pretty disappointing," said Kellock.

If the captain's reluctance to play the "bad luck" card was admirable, it also sold Glasgow a little short. Had Jackson survived to play the whole 80 minutes as he had played the first 30, Glasgow would have had a losing bonus point as a bare minimum.

As it was, the Saints took advantage of the injury fall-out to stretch away after the break, Stephen Myler and Vasily Artemyev securing the tries that ensured full value from the win. By the end, Lamont had gone the same way as Hogg and Jackson, leaving the Scots with a disjointed back-line featuring a flanker in midfield and a scrum-half on the wing.

Lawes going the full distance, along with his fellow England forward Tom Wood, brought smiles to the faces of the watching national coaches Andy Farrell and Graham Rowntree. But on balance, Andy Robinson and his new colleague in the Scotland think-tank, Scott Johnson, took more from the game. Northampton play pretty much like England – big scrum, ferocious physicality at the breakdown, hard running in the wide channels – and for a while at least, Glasgow showed how to deal with it.

Northampton: Tries G Pisi 2, Myler, Artemyev; Conversions Myler, Lamb. Glasgow: Tries Strauss, Lamont; Conversion Jackson; Penalty Jackson .

Northampton Wilson (Lamb 57); K Pisi, G Pisi ( May 71), Waldouck, Artemyev; Myler, Dickson (Roberts, 73); Tonga'uiha (Waller 71), Hartley (capt; Haywood, 78), Mujati (Doran-Jones 66), Manoa (Sorenson, 64), Lawes, Dowson, Wood, Oakley.

Glasgow Hogg (Murchie, 10); Seymour, Dunbar, Horne, Lamont (Gillies, 67); Jackson (Matawalu, h-t), Hyrgos; Grant ( Fainga'anuku, 71), Hall, Cusack, Swinson (Ryder, 52), Kellock (capt), Strauss (Eddie, 64), J Barclay (Fusaro, 57), Wilson.

Referee R Poite (France).