MR PORTER meets the British funnyman the US is taking very seriously.

Mr James Corden has a cold. But not in the Mr Frank Sinatra sense. After a two-hour shoot at Smashbox Studios in west Los Angeles, he’s on the sofa, coughing and sniffling through the interview. But he doesn’t grumble. He doesn’t reschedule. In fact, he looks delighted to be here.

“Oh, I can be Oscar the Grouch sometimes,” he says, grinning. “But what’s the benefit? Because let’s be honest, I technically should not be on MR PORTER. I’m probably the heaviest person you’ve had. So this is a picnic. If a magazine says, ‘Let’s do that guy,’ who am I to say anything but, ‘What a day! What a joy! What a life!’”

Mr Corden has every reason to be cheerful. His 2015 was off the charts. Not just because of the OBE (for services to drama) or the Christmas single with Ms Kylie Minogue, but because he took an enormous gamble – he moved to LA to host The Late Late Show on CBS – and it paid off. “I was so convinced it wouldn’t work that we rented all our furniture for a year,” he says. “I mean, I’ve never hosted a chat show before. I’m not a stand-up. I’m not even a sketch comedian.” He’s also the youngest ever late-night host and, at the time, he was so unknown in the US that when he started work and forgot his pass one lunchtime, the CBS security guard refused to let him back in.

Today, Mr Corden is a household name. A pal of the Beckhams, Ms Anna Wintour and Mr Gordon Ramsay, among others, he recently had his contract extended to five years. “So yeah, I did buy a sofa last week,” he laughs. “They can still fire me, but I can’t leave.”

How much does the US love him? The show’s YouTube channel has had more than 600 million views. As Mr Corden says, “Good numbers if you’ve been on Saturday Night Live for 10 years.” And critics are hailing The Late Late Show as part of a cultural shift in late-night viewing away from what Mr Corden calls “the more caustic atmosphere” of Messrs Jay Leno and David Letterman, to a modern era of goofy fun, epitomised by Mr Corden and Mr Jimmy Fallon on NBC. They’re younger, chummier and happier by half. Mr Leno himself has said, of Corden’s success, that “the era of ironic snarkiness is over in America”. It’s all about joyful virality now – Mr Fallon’s Lip-Sync Battles, Mr Jimmy Kimmel’s Mean Tweets and, of course, Mr Corden’s breakout hit Carpool Karaoke, in which he gives famous people (such as Ms Mariah Carey and Mr Justin Bieber) a lift to work and asks them to sing along to their own songs on the car stereo.

“When we started it, everyone said no,” says Mr Corden, checking the latest numbers on his phone. “But now there’s a queue. Adele’s one has had more than 64 million views.”

In person, Mr Corden is a calmer version of his TV persona. He’s still upbeat and friendly, but more thoughtful. Every question is given serious consideration. “I think the news is different today,” he says. “So it’s my job to make the last hour of your day a lighter one. And guests don’t need the talk shows as much as they used to. TV is just one of a number of platforms now, so I need to make sure they enjoy it, because otherwise they might not come back.”

The show is exactly as he pitched it in his first meeting. He was starring in the hit Broadway play One Man, Two Guvnors when the call came to meet Mr Leslie Moonves, the CEO of CBS, and Ms Nina Tassler, who at the time was the company president. They’d seen his play and wanted him to replace Mr Craig Ferguson, the former Late Late Show host. So Mr Corden proposed a “fun, youthful show that the internet would respond to”. By the end of the meeting, he had a job offer.

“I was really reticent,” he says. “I said no, and then it went quiet for a few weeks. Then I said no again.” He’d have to shelve some big plans. He was writing a sitcom for HBO at the time, and planning a return to Broadway. But his friend Mr Piers Morgan was urging him on. He said, “It’s a fierce and unforgiving place, but you’ll regret not trying.” And in the end, Mr Corden’s mind was made up. “I thought, it won’t come round again. In five years’ time they won’t go, ‘Oh, let’s go back to that guy who turned us down.’”

At that time, Mr Corden’s career was already a thing to marvel at. He’d had a modest upbringing in Buckinghamshire – his father was an RAF saxophonist; his mother, a social worker – and was so desperate to perform that he skipped college and went straight to work at 17, going from one amazing milestone to the next. There were bit parts on television, then a Mr Mike Leigh film, a play at the National Theatre, and three seasons of Gavin & Stacey, the sitcom that he both co-wrote and starred in. Before he left for the US, he’d hosted the Brit Awards, won a Bafta, then a Tony, and was well on his way to becoming a national treasure. All this, and he was still only 36.

The only lull came around 2009–2010, when a lot of going out and a few ill-advised comments spawned a tabloid backlash and the image of an arrogant party animal. Today, Mr Corden insists it was all overblown. “I was writing the third season of Gavin & Stacey, so if that was my low point, then great.” he says. “But I’m grateful for it. Because after going through such a severe kicking, it’s very liberating to know that it didn’t really end anything.”

The truth is, Mr Corden was never the party type. He barely drinks. And since meeting his wife, Julia, a former charity press officer, he settled down very quickly. “I was only ever going out to find someone to stay in with,” he says. One of the reasons he took the LA job was to stay close to his children – Max, four, and Carey, one – as opposed to spending months away on location as an actor. “My whole life revolves around them,” he says. “It’s pretty straightforward.”

His only extravagance is clothes. “Yeah, I like fashion,” he smiles. “I know it gets a bad rap, but trust me, there are dickheads in plumbing, too.” His label of choice is Burberry. He starred in its Christmas 2015 campaign and, following a skit with Ms Naomi Campbell on The Late Late Show, he even walked the brand’s catwalk last April, at its London In Los Angeles fashion show.

As our time draws to a close, I ask Mr Corden what lessons he’s learned along the way. And, as always, he gives it some thought.

“If you’re not given a seat at the table, make your own,” he says. “When I was coming up, I was never on the One To Watch pages, like my friends. It felt like the industry was saying, ‘We think you’re good, but we’d like you to play the man who drops off a TV to Hugh Grant in a movie. And these other people will go and be stars.’ So I wrote a TV show for myself. I muscled my way in.”

Another motto is: the harder you work, the luckier you’ll be. “I’ve learned not to think, ‘Right, I’ve made it. I’ve made a Mike Leigh film now, this will change everything.’ Because it never does. That pinnacle doesn’t exist. All you have is the work you’re doing now. So don’t look ahead to the next thing. Just do your best in the moment. Be the best father, talk-show host, MR PORTER interviewee or whatever, and you’ll always be a success.”

He wants to say something else, but he’s coughing too hard. “Sorry,” he says, in a strangled voice. A quick drink of water and another lozenge and he slumps on the sofa, red in the face. Does he want to call it a day?

“No, no, I’m fine. This is important.” He sits up again. “I was saying, no matter my age, I’ve never appreciated how young I am. Like when I was 15, or 21, or now even. And I guarantee you, when I’m 50, I’m going to look back at me at 36 and go…” He spreads his arms wide, and looks up at the ceiling, mouth agape. And addressing the light fitting, he implores, “If only you could see how possible everything was.”