They are in danger of running away with rugby, these French. The Springboks may have something to say about that, but South Africa do not have the Top 14. And they definitely do not have Union Bordeaux-Bègles.

Leinster tried to contain them. Leinster, packed with experienced internationals, dripping with silverware, were desperate to avoid yet another agonising defeat in this final. Leinster were rudely introduced to the concept of absolutely crushing defeat. They were destroyed, made to look one-paced by a team of exuberant artistes who play rugby as if they simply love it, as if playing brilliant rugby were the most obvious and natural course of action. Like breathing.

To be in the San Mamés Stadium in Bilbao on a suffocatingly hot afternoon, among tens of thousands of jubilant Frenchmen chanting “Allez, allez, UBB!” with the same kind of relentless exuberance of the team itself was to be reminded that there is nothing like domestic sport for intensity and colour.

Of the major team sports, rugby union is the only one for which international competition is the primary engine (now that Test cricket seems on the wane relative to the shortened game), but the further the sport ventures into its professional era the more we can expect to see it conform to the model of the others.

Domestic sport is what supplies fans with their regular diet of weekly action; international sport is the spicy delicacy every now and then. They say UBB are the best-supported rugby club in the world. Such was the all-round exuberance, it is difficult to imagine any national team, even in rugby union, inspiring the same.

And, to think, Bordeaux are fifth in the Top 14, with two rounds to play. They will likely make the playoffs, so no one will be discounting them from winning a first title, although versions in the 19th and 20th century have claimed the Bouclier de Brennus, the fabled winner’s shield. But it is sobering to note their modest standing in the current table and inspiring to see them wed such history, culture and passion. In the brash, bold 21st century that tends to mean, too, endlessly ringing tills.

No doubt UBB will claim the French crown soon, but they now join an elite who have successfully defended this trophy. The scoreline looks decisive, but it really tells only half the tale: the first half, during which that team of Irish internationals were blown away.

As much as any other, this was redolent of that opening game of the Six Nations, when Ireland were blown away in Paris. It felt then very much as if one team were on the wane, the other on the up. Ireland did manage to summon some form to finish the championship strongly, and Leinster are well placed for another tilt at the United Rugby Championship, but any advice to buy the French and sell the Irish looks as wise now as it did then.

Leinster have felt the heat lately of general criticism. Leo Cullen seemed as irked after their semi-final win over Toulon in Dublin by the nonplussed reaction that has greeted so many performances this season as he was excited to be in another Champions Cup final. But he will find it hard to argue after this that all is well in a province used to such high standards.

To compare the two teams on paper was to note that long list of familiar Irish names against a list that boasted more than a few shining lights of unparalleled brilliance but more than a few names, too, that you would really need to know your rugby to have heard of. When Tommy O’Brien was worked over in the corner for the game’s first try a recapture of Leinster’s former glories seemed more than possible. And then reality struck.

Among those points of reference in the UBB lineup, the heart and soul is Maxime Lucu. His duel with Jamison Gibson-Park always looked to be pivotal, but there was only one bald maestro in it. Lucu it was who darted over for UBB’s first try two minutes later, Lucu it was who converted seven shots at goal from seven. He did spend 10 minutes in the sin-bin early in the second half for, perhaps jealously, tugging the hair of Joe McCarthy, but the game was long gone by then.

McCarthy responded with the next try while he was away, but Lucu returned to kick two penalties, one from his own half, to put the match even more out of reach than it was by half-time.

This was a personal triumph for the man they call the king around here, having grown up in the Basque Country, just over the border in France. Again, the sense of meaning was palpable. Brilliant rugby shot through with soul. There could be something in that. Allez, allez, UBB!