Surely that kind of enduring success, in conjunction with that kind of cash, has rotted his soul? Surely Norton's on-screen persona - so harmlessly camp, so relentlessly cheery, so relatable, classless and Irish, so nice - is a ghost of the person he used to be, before success transformed him into something darker, meaner, more ruthless, more ego-driven?
Apparently not. On top of him being convincingly pleasant in the flesh, when I ask around - friends of his friends, former colleagues, people who bumped into him that one time in a random green room somewhere - I come up with nothing but gushing endorsements.
You have a weirdly good reputation, I tell him. "You haven't asked the right people," Norton says.
Who should I have asked? "Showbiz stringers. I'm horrible to them."
Are you a good person? "Am I a good person? No! If I were a good person, I wouldn't be doing the job I do. I'd be helping! I'd be scrubbing up right now to tend to sick children in a hospital. Clearly, my life is a very selfish life. So to that point, I'm not a good person. But I hope I'm a decent person."
What makes a decent person? "I've tried not to make enemies along the way."
Successfully? "Pretty successfully. I've got one I'd like to be an enemy. One I'm actively trying to make into an enemy."
Who? "I can't tell you!"
Is he famous? "No. Well. Ish. No. No! I mustn't!"
Why make an enemy of him? "Because ... enough already! I don't want him in my life any more!"
Norton is publicising a new book, a memoir called The Life And Loves Of A He Devil. I tell him I like it, of course. It rarely flies to tell a subject you don't think their latest project is all that; but it's also true. He Devil is no elegantly crafted literary work but it's funny, goodhearted and sincere. It's divided into eight chapters, each describing one of Norton's longstanding passions: from dogs to Ireland, boys to booze (of which, Norton writes: "I may abuse [alcohol] ... but my relationship with booze is still based on enjoyment rather than fear. I know exactly why I'm drinking it, and while I may end up flailing around a dance-floor like a member of the living dead, I like to think I am in control of the bigger picture. Of course, I may be wrong."
This, after, describing falling asleep propped up against a lamp-post following an evening in a bar, and a one-off attempt at an AA meeting in the company of his friend, the actress Carrie Fisher.
This is not his first autobiography. Norton published So Me in 2004. The new one is, to some extent, a book about being gay. It isn't graphic, precisely, but it does refer to one-night stands, to boys doing what "boys sometimes do", to the morning after one particular night when one of his dogs ate a condom before Norton had time to dispose of it.
"I am a little bit worried about my family," Norton says. "Not that worried. They didn't read the last book. I told my mother not to; there was stuff in there that she didn't know about, lies I'd told her. I thought: 'Easier for her. She'll worry if she reads it'. And my sister, who I didn't ban from reading it ... We were having dinner one night and my sister was there, and someone said something about the book. It turned out my sister hadn't read it. Somebody asked why not, and she said - without trying to be mean, she was just being very honest - 'Well, there are so many good books to read'."
Jono and Ben at ten's jono Pryor and Ben Boyce with Norton, filming for the chat show host's Show in London, in May.
In the book, and in life, Norton does a good job of seeming as if he never really struggled with his sexuality. He was born 51 years ago; he grew up Protestant in largely Catholic Bandon in County Cork, and he says he put down any early feelings of alienation to that, rather than a burgeoning knowledge of his true nature. His book describes a childhood of willing, cheerful aloneness, an awful lot of telly and few friends; there was his mum, Rhoda (a member of the local Mother's Union), his dad, Billy (a Guinness salesman, who died in 2001), his elder sister, Pauline (now married with children, still living in Ireland), and a succession of pet dogs, but not much in the way of other company.
He accepted he was gay in fits and spurts; had a fumble with a male French exchange student when he was 17, a relationship with a girl he met when he ran away from University College Cork and joined a hippie commune in San Francisco, aged 20. He lost his virginity to another hippie on the commune - a man called Obo, whom he suspects wasn't gay, just kind, "and a hippie, so he felt obligated".
When Norton got to London in the late 80s and started working as a waiter in a restaurant in Covent Garden, everyone he met simply assumed he was gay, "and I didn't say or do anything to contradict them. After about a year, I was a fully out gay man living in London."
Well, not quite fully: his parents found out officially some years later, when Norton - by then a TV star - dropped a casual reference to his sexuality on air. His mother phoned to ask why he hadn't broken the news directly, and he replied, "But you told me not to upset my father."
Norton's said, in the past, that he had more of a problem coming to terms with being camp than he did being gay. I say, I'd rather assumed campness was an affectation, a way perhaps of announcing more clearly to the world that you are gay and unashamed.
"No, because you meet those men who are very, very fey, and you assume that they're gay and then you discover, 'Oh my God, you're straight!' There are just some men who are a bit light in their loafers.
"And then, you're right, there is a chosen bit of it: 'Oh, look at her,' and all that, that's learned stuff. But you see little boys, and for Christmas they want a pink bicycle with a basket. That's not learned."
Why is campness so hard for him? "Because it's not admirable. It's not desirable."
Because of societal ideals about masculinity?
"Yeah, and because there's still a lot of self-loathing within [the gay community]. I remember, I saw a documentary on something to do with being gay. And there were these kids being interviewed. They were talking about me, and how I was a very bad role model and da-da-da. And what was heartbreaking was that they were me. They were just four little camp boys who lived in whatever town they lived in. And they didn't want to be me."
Why not, I ask, wondering if that was all that had broken Norton's heart about these boys' revelations. "Because nobody wants to be me."
I tell him I think it's significant that one of Britain's highest-paid, most-watched TV stars is openly gay.
"Um," he says. He pauses. "I think it kind of is significant. But I don't think I did that. I think it happened around me. I think I was very lucky when I showed up, that things were changing. I don't think I changed things. People say, 'Gay's become mainstream'. I don't think it has. I think it's sort of dissolved into the mainstream."
If the book is anything to go by, Norton is pretty adept at meeting men. ("People ask me if I'm worried that some men might be interested in me just because I've got money and I'm off the telly," he writes. "Hopefully, they date me for other reasons as well, but the reality is that if they don't like wealthy, well-known men, they really shouldn't be dating me.")
He seems less successful, however, at sustaining relationships with them. In his early 30s, Norton began a five-year affair with an American called Scott Michaels, who moved from the States to be with him in London, but things fell apart when Norton became famous. There was a tumultuous affair with a younger New Yorker called Kristian Seeber (whom Norton refers to repeatedly in the book as a "bad boyfriend", a description, he says, he cleared with Seeber, who agrees it's fair), which ended in 2006. Most recently was a two-year relationship with Trevor Patterson, a Canadian software designer 20 years younger than Norton. That ended mid-last year, after which Patterson sold a story on Norton to a newspaper.
Norton and Former partner Trevor Patterson in 2011. The star says gay relationships are inevitably problematic if one half of the couple is famous. Photo / Getty Images
You've been kissed and told on, I say. "Twice," Norton says. How was that? "The first time was fine. That was Scott. My agent and I negotiated his deal. He'd been approached by somebody. I said, 'How much have they offered you? Well, that's not enough. We'll get you more than that.' I didn't take a cut, but I did have picture approval, so it was all good. The second time was disappointing."
Patterson's story of woe detailed Norton's heavy boozing and his obsession with his dogs; scurrilous highlights included the time Norton chartered a private jet to fly Madge and Bailey to New York where he was working at that point, because he missed them. Patterson is not mentioned in the new book.
Norton's single again. He thinks gay relationships are inevitably problematic if one half of the couple is famous. "Every man, no matter how young and twinkly he might appear, has a bit of alpha in him. Society hasn't quite figured out how we deal with that. If I were a straight guy, in my job, I could easily have some nice young lady, in her gorgeous gown, and she could play hostess, and she might pop a baby out, she'd have something to do, people could see her function. Whereas if you're a guy, he's so emasculated by it, and that is difficult."
Would Norton consider dating another celebrity? "Do you know what? It's just hard to go out with someone my age. They don't want to go out with me. I would like to go out with someone my own age. But that seems impossible."
Because gay men your age want to go out with ...? "Younger guys!"
All of them, apart from you? "I don't mind going out with younger people. But it seems weird. When I was younger, I didn't go out with older people."
He isn't on any of the gay introduction apps, but he has tried dating sites, "which aren't just sex hook-ups".
Isn't online dating impractical if you're famous? "I've never met anyone. So, I guess: yes. But I'm sort of glad in a way. I've seen friends become really obsessed by some of these sites. Desperately chasing this one guy ... 'Oh! He's on again! He's on the thing!' All that sort of stuff. I'm quite glad I don't have to do any of that. All this technology's happened post me being on telly, so it's not like I've had to wean myself off them."
I ask Norton if he's ever wanted children, and he says: "Looking back, I regret - and I don't use that word often - but I suppose, I do regret not having kids."
You feel like it's too late, you've missed your chance? "Yes. When it was appropriate, I didn't. When it was appropriate, I could hardly look after myself."
Would he have been a good father? "Who knows?"
Would he have opted for surrogacy, an arrangement with a female friend, adoption?
Norton seems uncharacteristically banjaxed by this line of questioning. "Erm ..." he says. "No. Erm. I don't really ..." He regroups. "That's the other thing. Talking to young gay guys ... Because of people like Elton and David, and Tom Ford, it's now become a 'thing'. Gay guys are really like, 'Yeah, I'd like to have kids. I want to have kids.' I'm like, 'How are you going to do that? Because it's gonna cost - thousands and thousands!'
"I think what they've been told is, it is possible. Previously, one of the things about being gay was you didn't have kids. Now you can be in a relationship, you can get married, and you can have kids."
I point out that he could afford it, however, and although he may feel he's too old, this is still doable. He says, "I like the idea of being a father but how would I do it? I'd probably just end up with teams of people looking after this baby, whom I saw ... sometimes. My schedule is very different from a baby's."
Does he have Madge and Bailey instead? "No. Dogs are more like replacement boyfriends, I would say, than babies. I do think people who aren't dog people think, 'Oh look, there he goes with his gay fur babies.' I don't care. I am aware that my dogs aren't people. I don't buy them Christmas presents. I don't sign their names on letters or cards. No. It's an animal."
Norton's chat show pulls in an average of four-and-a-bit million viewers every week.
Norton is not a great beauty. His face is wide and open and engaging, but part of his wide-reaching appeal as a broadcaster hinges on his being nice to look at, rather than intoxicatingly handsome. He's inclined to denigrate his own looks - and also, the good looks of others. "[Age] is the world's revenge on pretty people," he once said.
He lost a substantial amount of weight early in his TV career: "It's a very cruel mirror, telly," he tells me now; and weight appears to remain a pre-occupation. When I ask him about his experience of the ageing process, he says, "Weight is annoying. Weight becomes harder to shift. I try to keep it off."
Does he think he is fancied? "No. I think if the world were gay, I don't think builders would be wolf-whistling when I walked by."
Is he vain? "Yes. Everyone's vain. But listen, if I were obsessively vain, I think I'd look better than this. I suppose it's that winning combination of vanity and laziness. You look at yourself and you think, 'I should go to the gym more, I should whiten my teeth, I should get my eye bags done, I should have a hair transplant ... or I could have another glass of wine and watch some telly and take fewer pictures'."
I ask him if he's glad, in respect of ageing, that he's not a woman. "Yes." Because TV is crueller to women? "Because society is crueller to women."
Crueller to women than it is to gay men? "I think it is. I do."
We talk about his years working as a waiter in San Francisco and Covent Garden. I tell him I think ex-waiters and bar staff make the best celebrities. Norton says, "I think it makes for a better everybody. My friend says it should be like national service. Instead of going into the army, everyone should work in a bar or restaurant. I was talking to someone yesterday - it was a trainer; there, I've said it! - and it's this gym in the city, so there are lots of rich guys there, telling him about their kids, and how they're out of university now and they're just sitting at home, not doing anything, because there are no jobs out there. And you think, 'Crap! Just get a job! Become a barista! Do something!'
"Doing those sorts of jobs, not only do you become a nicer person to waiters in later life, but also, you figure out how to read people. You discover that a lot of people are vile, you discover how easy it is to be nice, how easy it is to be a shit, how easy it is to avoid being a complete shit. Just do a job! Why sit at home? You're going to learn nothing staring at a wall in your parents' house."
He says he can still remember having no money, that the best thing about being rich is, "the simplest thing. A bill arrives, and you don't shit yourself."
He's unusually good company for a famous person. He's brighter than he pretends to be; I don't think he gives me a single answer that feels lazy or rehearsed. On top of which, his accent is a cliche of charm. Maybe you can get away with saying more risque things if you're Irish. Norton once called Raquel Welch a "grumpy old bitch" live on air, before hanging up on a satellite link with her. No one ever complained.
He tried and failed to break America in 2004, but he's made peace with that. "We haven't pushed it, that idea of going [back] to America," he tells me.
Does he have any unfulfilled ambitions left? "Not really."
Norton's said in the past that he was amazed his career had lasted as long as it had. "And now? This is stupid; this is 10 years later!"
Did you assume you'd have fallen on your arse? "Not fallen on my arse, but I thought it would have wound down by now. I've signed up for another three years, and after that I'll be 54, 55. And that might be a nice time to stop. But I thought I'd stop at 50. And when you get there, you're kind of still quite enjoying this. So ..." So you carry on? "Yes."
Finally, I ask Norton if he's happy. "I'm not unhappy. Content is what you aim for. Happy is when the lovely things happen. You can't live your life like that, or you'd be a lunatic. You've got to aim for some sort of middle ground."
The Life And Loves Of A He Devil by Graham Norton (Hodder & Stoughton $39.99) is out now. The Graham Norton Show is on Fridays at 8.30pm, TV3.
