Anyone who felt the Taoiseach was a bad choice for the opening guest -- let's face it: he's hardly the most appealing presence at the best of times, let alone the times we're living in -- or imagined that Tubridy would be giving him an easy ride, was in for a surprise.
This was a brilliantly handled interview: tough, tenacious, canny and uncompromising. In fact it may well be the best television grilling anyone has given to Brian Cowen or any other sitting Taoiseach.
After some brief pleasantries about how well the Taoiseach looked (Cowen seems to have had a fresh haircut for the occasion) and a couple of polite enquiries about his health and state of mind, Tubridy went at it like a ferret after a rat.
How about that disastrous opinion poll? The Taoiseach described it as "a distraction"; Tubridy suggested, wryly, that some might consider it more than a distraction.
"What do you accept the blame for, Taoiseach?" asked Tubridy, reminding Cowen that as Finance Minister he'd ignored the advice of "a slew of economists" who warned him not to spend too much money.
Grumbling that people were now accusing him of not spending enough money, Cowen tried to divert the conversation in the direction of Lisbon, which Tubridy headed off with a polite but firm "we'll come to that later".
Did the Taoiseach think he should apologise? Cowen said he'd apologise if he thought he'd done anything to apologise for. "You see, that's not really an apology," said Tubridy. "I don't really know what that is. Do you apologise or not?"
Cowen harked back to how, in the good times, our growth rate had been faster than any other country's. "But that doesn't matter now, does it?" said Tubridy, by now on his third round of spontaneous applause.
Then it was on to TDs' and ministers' expenses, and how anyone can justify blowing €9,000 of public money on a jaunt to the Cannes Film Festival. "Obviously, that shouldn't happen," began the Taoiseach. "But it did happen," countered Tubridy sharply.
The questions were fast, furious, angry and unrelenting -- about NAMA, about the budget, about who would feel the pain -- and left Cowen on the back foot. More T-shock than Taoiseach, if you like.
Suddenly, in the midst of all the heat, Tubridy paused and switched tracks: "Do you like being Taoiseach?" Cowen, like the audience, laughed -- more out of surprise and relief, I imagine, than amusement.
Just as smoothly, Tubridy changed gear again to quiz the Taoiseach, delicately yet frankly, about newspaper allegations of heavy drinking. "Do you drink too much?" he asked. "No, I don't," said Cowen, adding (with commendable honesty) that he disliked "politically correct stereotypes".
Careful not to overstep the mark, Tubridy added: "Am I annoying you already? I feel it's a personal question, even though I asked it."
Cowen came back with the most telling comment of the evening, which also drew the biggest laugh of the evening: "No, look -- it's your show." It certainly is!
Tubridy's skill lies in his ability to recalibrate, to shift up or down the scale according to the person facing him. After a gripping, intense first quarter, he breezed effortlessly and charmingly through encounters with Brian McFadden, Joan Collins, Cherie Blair, Saoirse Ronan, and Niall and Gillian Quinn.
By the end of his first Late Late, Tubridy had the confident air of a man who knows he now owns the programme outright, and that it's his, and no one else's, for as long as he wants it.
"Let's do it all again next week," he said. Yes, Ryan, let's.
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