As defeats go, Edinburgh’s 31-18 loss to Clermont Auvergne on Friday night was one of the more acceptable ones. They would not say so themselves, of course - captain Ben Vellacott declared they had been agents of their own downfall in the Challenge Cup tie at the Stade Marcel-Michelin - but there were definitely extenuating circumstances.

First of all, this was an Edinburgh team deprived of Pierre Schoeman, WP Nel, Grant Gilchrist, Jamie Ritchie and Ben Healy. You can say what you like about squad depth - and there is no doubt that it is steadily improving under senior coach Sean Everitt - but any team would be weaker without that quintet.

Secondly, the Challenge Cup has a forgiving format. The top four teams in each pool go through to the last 16, so the defeat in France is far from fatal. If they beat Castres at home on Saturday, Edinburgh will be back in the mix. They then face Gloucester at home and Scarlets away next month, and are capable of taking points from both.

Certainly, while critical of aspects of his team’s performance against Clermont, Vellacott insisted he retains confidence in their ability to be competitive at this level. Indeed, having been part of the team that beat Castres twice in last season’s Champions Cup, he believes they have already demonstrated that they have the requisite quality in their ranks.  

“I think we proved that last year in terms of where we sat in the Champions Cup,” he said. “We played Saracens a couple of times, beat them at home and just lost narrowly away. We beat Castres twice. So we can obviously compete at the top - we just need to be really consistent with that when we actually get our opportunity.

“Castres are going very well in the Top 14 at the moment. We know that’s going to be really difficult, but if we perform well in that, that puts us in a good place in terms of where we sit in the pool.

“We played them home and away last year, and I played in both. What’s the key to beating them? Pretty much the same as most French teams - keep the ball in play for a long time, try and tire them out, be really accurate with the ball and don’t give them the ball easily so they can get their set piece going.”

Edinburgh managed to apply much of that formula against Clermont in a scoreless opening quarter before falling 17-0 behind. But full-back Tim Swiel gained them a foothold in the game with a penalty just before the break, and in the second half they went from 17-3 down to 17-13 when Javan Sebastian scored a try converted by Swiel and Cammy Scott added a penalty.

That was as close as they would get, however. Clermont gave themselves a huge energy boost by bringing on seven substitutes at the same time, and two further touchdowns ensured the bonus-point win. Edinburgh had the last word when Wes Goosen added a late consolation try, but they had no chance in the few remaining minutes to get a third try that would have at least seen them head home with a losing bonus point.

“We made life pretty difficult for ourselves and gave them a little bit of oxygen from our mistakes,” Vellacott said. “We fought hard for the points that we got, but we let it slip towards the end through our ill discipline and silly errors, which gave them the game. 

“To be fair, they took their chances. We’re obviously really disappointed, but I’m really proud of the boys in terms of their fight.

“Their subs made a good impact just as the game was turning. We had a lot of momentum at the time then their subs came on and obviously changed the game for them.”

At least some of the five senior players who sat out the journey to France are expected to be back to face Castres at the Hive Stadium - Gilchrist, for example, has been rested for the last two matches, so will be itching to get back in action. And winger Darcy Graham could make his first appearance since the Rugby World Cup after recovering from injury.