'It's a weird lifestyle," says Paul Giamatti, on the lot of an actor. "Weirdly all-consuming ... It's just odd -- a very strange way to live. And the people are strange, and you are kind of given weird carte blanche to act like a lunatic a lot of the time. It's hard to shut that off sometimes. So it's not easy for the people around you."
Giamatti must, without doubt, be the most un-starry film star ever. There is no sign in him of the perfect self-control, the effortful social polish that is the hallmark of a consummate actor. Instead, he's an average man in trainers and an unglamorous grey cardigan, who, nevertheless, is utterly charming.
And yet, as actors go, Giamatti has lately become about as celebrated as can be. Last week, he was handed a Golden Globe for his incredible performance in Barney's Version, his new film, based on the book of the same name by Canadian author Mordecai Richler.
Perhaps, the mechanics of his craft aside, part of Giamatti's appeal is his reach-out-and-touch-him realness. He doesn't dazzle like an idol. There's no sleight of hand. On screen and in life, he seems incapable of being fake.
In interview, he doesn't deliver witticisms or perform tricks. In fact, though unfailingly polite, something about his delivery suggests that underneath the manners he finds the process a little embarrassing and perhaps even absurd.
A few years ago, talking to Esquire magazine about giving interviews, he said: "I try not to do a whole lot of it. I get tired of myself pretty fast. So I can't imagine other people don't get tired of me."
How did he get on with Dustin Hoffman, who plays his father in Barney's Version, I ask. A funny little laugh escapes from his mouth.
"He's a good guy," he says, smiling. "He's kind of like the character he plays in the movie. And at first I wasn't sure if he was doing some sort of method-y thing, where he was sort of being the character. But I think he actually is sort of like that. He's got amazing energy for a guy his age, and he's just a lot of fun to be around. He can't calm down, he doesn't shut off, he's got no self-editing device. Whatever comes into his head just comes out of his mouth. And it's kind of amazing that he doesn't come off as offensive at all.
"If I said half the sh*t that he said, I would get thrown in jail. But for some reason it's OK. It's like, most people would think that you are a complete dirty old man. But you're getting away with this! I could never get away with it. It was enviable."
Giamatti became a household name after the success of indie film Sideways. It was in that film that he was first spotted by Barney's Version producer Robert Lantos, who had been incubating the book's adaptation for several years.
"We needed an actor," Lantos says, "who had unconventional looks, and great talent, and, above all, great intelligence as an actor. Intelligence that was visible on-screen."
Since Sideways, Giamatti has developed the reputation as a virtuoso, not least because of the way he has defied typical Hollywood definitions, to become a leading man who plays neither pin-up nor hero.
So though he says he is nothing like his character Barney Panofsky, ("He's a nightmare!") they have something in common, both charismatic in an almost accidental way.
Originally from Connecticut, Giamatti's father was president of Yale. Before he got into acting Giamatti was on course for an academic career himself.
He now lives in Brooklyn with his wife Elizabeth Cohen and their nine-year-old son Sam. He met Elizabeth at Yale, when he returned there to study drama after an abortive attempt at a career in animation. The choice of the east coast seems to fit with his rejection of glitz.
"I like Los Angeles, actually, a lot. I just never had to move there and I would rather live in the north-east, which is where I'm from," he says. "I need changes of season and things like that. And the desert freaks me out a little bit."
Life, for him, involves regular adjustment between the intensity of the on-set experience, to full-time family life, and back again. "I've long stretches of time when I'm around (at home) all the time ... don't know if that's necessarily a good thing because ... I get antsy about work. It's weird. You'll have these periods of intense activity and then nothing to do for a while," he says.
Though the critics have taken him to their bosom, he doesn't buy into the hype.
"It's nice to have people like what I'm doing, but it makes me more sceptical."
Are you suspicious of a consensus? "Absolutely. I don't like people congregating. I don't like clubs and crowds. It makes me nervous."
In Barney's Version, the film encompasses a trajectory that includes most of a lifetime. When the action begins Barney is 30, and we watch him as he ages into an old man.
I ask him a question about following a lifespan on film and try to tie this into a reflection on mortality, that to be fair is, at best, a bit of a stretch, and at worst bordering on waffle. He humours me, graciously delivering an answer to his cup of tea, and then shooting me a conspiratorial look at the end, which seems to acknowledge the preposterousness of this whole set-up.
"With this guy, (Barney) it was interesting to see how much he goes through and doesn't really change that much, and it makes me wonder how much people actually do change," he says. "I don't think people really do. You can have these up and down movements through your life but then in the end you're really not all that different. After everything he goes through, he's just a kind of magnified version of himself. He's no happier and he's no better at anything, and he hasn't really changed that much."
That sounds a bit fatalistic. Does he not think he has developed, or evolved over the years? "I guess so," he says, looking unconvinced. "It's hard to know. I've definitely behaved in unexpected ways, and done things I wouldn't have thought I would have done a long time ago. But whether in the end I'm that different? No. Sometimes I'm amazed that I'm 43, I still sort of feel like I'm 17.
"I continue to make the same kind of mistakes and the same weird choices. I'd like to think people can change, but I really don't know if they can. It's not a bad thing." And indeed, in his case it's certainly not. Consistency has served him well, and he's got his Golden Globe to prove it.