A lot of lip service is paid to the idea of the bonus point in the Premiership, but over a 22-match season the odd one here and there tends to be of limited significance. In the six-match bun fight of a pool in Europe, though, they really are "precious", the word that usually accompanies them (although sometimes they're "vital").

This is why the faces of Jim Mallinder and Dylan Hartley were not quite thunderous in the bowels of the Stade Pierre-Antoine after this shuddering encounter. Northampton's director of rugby and his captain did rue the lack of anything more substantial than a bonus, but a win at a place such as this – the home of the French champions, no less – would have gone past the precious and vital, and entered the realms of the "set you up for life".

"In the Heineken Cup," Hartley said, "you want to take points from every game, whether it's won or lost. We were hopeful coming here, because we wanted to take away four points, but they're a quality side, aren't they?"

They are both quality sides, or at the very least wincingly brutal ones. Northampton have long since let it be known that, if all else fails, they will pound you again and again, then do it some more. Castres were only too happy to meet that policy with their own defensive version of it, hammering into Northampton at the breakdown, preventing them from developing the prettier parts of their game, which tend to find the cracks to grow into once the pounding has done its work.

There were some fleeting flourishes of prettiness, but they were little more than brief intervals of light relief, a chance to go "ahhhh" for a moment, before the default belligerence resumed. Most of it came from Castres, who showed a pleasing, if largely ineffectual, aptitude for the off-loading game, in between the spillages elicited by all the collisions. "Castres play an unstructured type of game," Mallinder said, "and are very difficult to work out."

The whole club is a bit of an enigma. You wouldn't have known walking around beforehand that you were in the lair of the French champions. Not much more than an hour before kick-off the place was deserted, as the first vendors began to yawn and pull back the curtains on their produce. The first punters rolled up with less than an hour to go.

Then, boom. A small-ish town in the Tarn, east of Toulouse, Castres can hardly supply great swathes of support, but what a noise the happy few make, the drum and chanting a constant accompaniment to the pounding that takes place on the field.

It is an environment that would get to anyone. Northampton handled it all in their muscular, meticulous way, but even they were spooked into gifting Castres the try that would eventually cost them the win. In only the ninth minute, a rash pass from Luther Burrell was intercepted by Romain Martial, who galloped the 80 or 90 metres to the other end.

Now, that really might have got to them, but it is to the Saints' credit, and their set pieces in particular, where Courtney Lawes shone, that they kept things together and might yet have won. Hartley scored their only try, early in the second half, after Castres had pinched his lineout, only to let the ball bobble free for him to pounce on. Having just turned down a string of kicks at goal to set up camp in Castres's corner, Hartley was relieved to come away from that period of pressure with seven points. "All part of the gameplan," he knowingly smiled.

But one thing no gameplan could account for was the prompting and goal-kicking of Rory Kockott, Castres's scrum-half and amulet. "He is a fantastic little player," said Mallinder. "Whenever we made a mistake, he pinned us back."

All in all, to come away with a point from here might be considered more than just a bonus.

Castres Palis; Martial, Cabannes, Lamerat, Evans; Tales (capt), Kockott; Lazar, Mach (Rallier, 70), Peikrishivili (Wihongi, 52), Gray, Capó Ortega, Bornman, Faasalele (Wannenburg, 59), Claassen.

Try Martial. Con Kockott. Pens Kockott 4.

Northampton Foden; K Pisi (Elliott, 66), G Pisi, Burrell, North (Wilson 70); Myler, Fotuali'i (Dickson, 59); Corbisiero (A Waller, 66), Hartley (capt), Ma'afu (Mercey, 59), Lawes, Day (Dowson, 66), Wood, Clark, Dickinson (Manoa, 59).

Sin-bin Foden 32.

Try Hartley. Con Myler. Pens Myler 2.

Referee George Clancy (Ireland). Attendance 7,624.