Hooker Sean Cronin scored a pair of tries and loosehead Jack McGrath also crossed to put the Irish province in the driving seat as they went to the half-time interval 19-10 to the good.

Winger Isa Nacewa crossed for the bonus-point try in the 47th minute before the home scrum was rewarded with a penalty try after an hour. Anthony Jelonch’s late try for Casters’ was mere consolation.

Cullen was quick to acknowledge the work that scrum coach John Fogarty does with the squad in the build-up to each game and said: “John does a huge amount of work with those guys. A real strong culture there for the front rowers. They give really good hit-outs every week at training, some real good ding-dong battles there during the week at training.

“It’s sometimes that second team pack really puts the squeeze on the starters, so it’s a good competitive environment. I think it’s adding to the levels of the performance.”

Leinster had suffered a setback prior to the game when first choice fly-half Jonathan Sexton was ruled out with a hamstring injury but the highly-rated Joey Carbery produced an accomplished performance in his absence and Cullen was delighted with the 20-year-old.

He added: “I thought Joey acquitted himself well. He’s come into the team this year. He obviously made his debut last season, but he’s come in in pre-season, and he’s had a really good run of games, early season in the PRO12. He’s getting better all the time, he works incredibly hard. He’s a pleasure to coach, because you can see the energy that he brings.

“He’s a brave player as well. I thought he went well again. Similar to what he’s done so far this season. It wasn’t a great surprise. We were just delighted that it was another positive experience for him, because he works hard and wants to get better.”

French international scrum-half Rory Kockott was brought on off the bench for Castres, and while this was his side’s 10th away defeat to Irish opposition in the Champions Cup, he believes their problems on the day were more technical than psychological.

“I think it’s more of a technical problem, we have in the contact, I think. Leinster have really brushed up, and are really shining in that area. With regards to how they face the contact now, they face the contact part of rugby, which is almost every point of it,” said Kockott.

“I think in that point, we can take a little lesson home tonight and learn from it. They certainly had the upper hand, Leinster, in the first half. We didn’t. We found ourselves behind a great driving maul.”