Guest appearance comes too late as Saints sneak off with the points

Harlequins may well be the quickest side in the Premiership – judging by some of their scrummaging, they even retreat faster than everyone else – and the combination of fine autumn weather, firm playing surfaces, a sympathetic run of early fixtures and refereeing interpretations that deal all the best cards to the attacking team has propelled the Londoners into "Christmas comes early" territory. So much for the theory. If Quins continue to throw away victory opportunities like so much cheap wrapping paper, the reality will turn out to be very different.

There were more than 4,000 empty seats at the Stoop for the visit of the big beasts from the Midlands and if this had something to do with live television poking its nose in – a 1.30pm kick-off is far from ideal when little Lucinda is still playing lacrosse and jolly Jemima has barely finished mucking out the horsebox – the recent reappearance of the fake blood scandal in the popular prints might also have impacted. At its rollicking best, the Quins support has a "16th man" quality about it. Here, the 16th man stayed in the dug-out.

As a consequence, Northampton were able to hold themselves together sufficiently to cling to the narrow advantage accruing from Dylan Hartley's late try and sneak out of town with the four points, which was three more than their due. If it was impossible not to admire their Trojan-like work in defence – both Tom Wood and Ben Foden somehow found ways of keeping their line intact even when the line had been crossed – it was equally difficult not to wonder at their hosts' generosity. "We'll put some teams to the sword, because we're creating a shedload of chances," said Conor O'Shea, their director of rugby. And missing a shedload, too.

One of O'Shea's principal problems is mathematically insoluble, on the basis that four into three won't go. His first-choice loose combination of Chris Robshaw, Will Skinner and Nick Easter is nicely balanced: the dog, the scavenger and the footballer complement each other beautifully, and provided their tight forwards hang in there (which is just about all they are capable of doing), they are equipped to cause problems wherever they go.

But in a perfect world, they would have just a little more pace about them, and as bad luck would have it, the man with pace to burn – Tom Guest, the second-string No 8 – is the man who cannot find a place in the starting line-up.

Guest's introduction midway through the third quarter – rather than remove Easter from the fray, Quins shoved the England No 8 into the engine room – was at the heart of a transformation in fortunes that should have proved decisive. Danny Care, ever alert to the mis-match against lumbering forwards three times his size, handled twice in a sharp assault on the Northampton 22, but it was Guest's sudden appearance in support that created a try for George Lowe that put the hosts ahead for the first and only time in the game. Three seasons ago, he was pulling that sort of trick on a weekly basis and looked uncannily like a forward with an international future. Since then, he has not played nearly enough big-occasion rugby to make a persuasive case for himself.

"We have the best No 8 in England, and we have one of the best No 8s in England," acknowledged O'Shea. "Tom has added a huge amount of physicality to his game and I've had words with Martin Johnson about him, to the effect that he should be back in the selectors' thinking. He'll play a good deal of rugby for us this season, but we all know what Nick Easter brings to our game. How do I deal with the situation? I take Tom out for an awful lot of coffees."

Harlequins: Try Lowe; Conversion Evans; Penalties Evans 3. Northampton: Tries Ashton, Hartley; Conversions Geraghty 2; Penalties Geraghty 2.

Harlequins: M Brown; T Williams, G Lowe, J Turner-Hall, U Monye; N Evans, D Care; C Jones (J Marler 44), C Brooker (M Cairns 44), M Lambert (J Johnston 44), O Kohn (T Guest 51), T Vallejos (P Browne 81), C Robshaw (capt), W Skinner, N Easter.

Northampton: B Foden; C Ashton, J Clarke (J Ansbro 84), J Downey, B Reihana; S Geraghty, L Dickson; S Tonga'uiha (R Dreyer 81), D Hartley (capt, B Sharman 75), B Mujati (E Murray 66), C Lawes (C Clark 75), C Day, P Dowson (M Easter 66), T Wood, R Wilson.

Referee: A Small (London).