Up to 700,000 people watched Ryan Tubridy’s debut on the Late Late Show on Friday night, but his predecessor was not among them. Pat Kenny was seen having dinner with his wife, Kathy, in Ragazzi, an Italian restaurant near their home in Dalkey.

When Tubridy’s team warmed up the studio audience before Tubridy Tonight, they would stoke up the crowd by saying: “This isn’t the Late Late Show.” On Friday night, Tubridy went out to welcome the crowd to the Late Late Show, words he admitted he struggled to say, given the iconic nature of RTE’s flagship show.

“But it came out today and it felt right,” he said backstage, shortly after his debut as the chat show’s third host.

Looking a little dazed after his first 120-minute show, Tubridy said he was glad it was over, hoped it went okay and felt happy enough.

“It’s been a very long few months since Pat announced his retirement and since I was invited to present it,” he said. “The word that kept swimming in my head, and had done till about ten minutes ago, was expectation. We weren’t dealing with Tubridy Tonight, it’s not an entertainment show, it’s the Late Late Show and all the expectations that go with that.”

The consensus among critics is that the presenter, who started at RTE doing book reviews for Poparama at 12, did well after a nervous start. Tubridy opened by thanking his predecessors Kenny and Gay Byrne “for making the show the institution it is” and acknowledging he had big shoes to fill.

He then challenged those detractors who dismissed him as lightweight on current affairs by treating Brian Cowen, the taoiseach, to an 18-minute grilling on the state of the country’s finances and ministers’ expenses. A visibly uncomfortable Cowen perched on the edge of a leather chair as Tubridy fired question after question in rapid succession. Perhaps due to nerves, he regularly interrupted the taoiseach when he might have got better answers by allowing more time for a reply.

Tubridy also broached the topic of whether the taoiseach drank too much, but seemed to be embarrassed about having asked it and didn’t probe.

The presenter challenged the former Westlife singer Brian McFadden about why he hadn’t moved from Australia to be near his two daughters after Kerry Katona, their mother, was filmed snorting cocaine in her bathroom recently.

A Kennyesque clanger seemed possible when he asked actress Joan Collins whether the “facial tics” of her character Alexis Colby in Dynasty were inspired by screen legend Bette Davis. But the 76-year-old Collins let him off, merely saying: “I had facial tics?”

Afterwards she couldn’t praise Tubridy highly enough. “He’s fabulous. I thought it was really great. He’s so easy, I can’t believe this was his first show. He [is] a terrific interviewer, really good, and I’ve done a few interviews so I should know.”

Collins said she found him “much lighter, more fun and much easier to talk to” than Gay Byrne.

Cherie Blair, another guest on the show, said: “I’m not sure we’ve got someone like him in the UK. I went on the Jay Leno show and the format reminded me more of that, although he doesn’t do the stand-up comedy sketch.”

The line-up also included Sharon Corr, singing her debut single and talking about her sister Andrea’s wedding; Saoirse Ronan, the Irish teen actress nominated for an Oscar for her role in Atonement; Niall and Gillian Quinn; and singer David Gray.

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