Can sex addict and reformed junkie Russell Brand conquer America (and can America cope with him)?

A narcissistic, libidinous entertainer with snake hips, hair like a crow's nest and a self-absorption bordering on the comical.

If Russell Brand imagined he'd have to delve deep into his own psyche for his latest role, it was an expedition that must have taken all of five minutes.

With the release today of his first big Hollywood movie, Forgetting Sarah Marshall, Russell Brand plumbs the depths of his personality and comes back up with . . . himself.

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And it appears to have worked for him. His louche stand-up comedian persona was unknown in America until a few weeks ago, but with the release of Forgetting Sarah Marshall, all that has changed.

Surprisingly, considering their puritanical tendencies, the Americans are now singling out Brand for praise.

Brand, in typical braggart mode, says: "I read recently that George Bernard Shaw once said: 'A reasonable man adapts himself to the world; the unreasonable one persists in trying to adapt the world to himself.' Well, I won't be changing, but America will be."

Love him or loathe him - and you would be hard pushed to find a third option - Brand's confidence might, at first blush, appear to be misplaced since the film has been panned by several critics here.

But while Sacha Baron Cohen has conquered the States with his twin creations of ineptitude, Ali G and Borat, Brand, too, is looking to make a similar impact after his pilgrimage to Hollywood.

Too bad then, that Russell missed out on an appearance on David Letterman's TV chat show this week because of a mix-up over his visa.

The funnyman was pulled aside by immigration officers at New York's JFK airport and sent back to Britain after eighht hours because his papers were not in order.

But having experienced highs (his autobiography, My Booky Wook, was a bestseller last year) and lows (his dismissal from MTV when he came to work the day after 9/11 dressed as Osama Bin Laden) in his career in Britain, he is looking to make a name for himself in America, as well.

Comedy star: Russell Brand with his co-star Kristen Bell in Forgetting Sarah Marshall

Forgetting Sarah Marshall follows the tale of Peter Bretter (Jason Segel), a middlingly successful television show composer who has just been dumped by his TV star girlfriend, the Sarah Marshall of the title (played by Veronica Mars star Kristen Bell).

In an attempt to alleviate his woes, he goes on holiday to Hawaii and ends up staying at the same resort where Sarah and her new boyfriend, preening rock star Aldous Snow (Brand), happen to be vacationing.

Disaster after disaster ensues as the film casts Brand as the foil with a lexicon of Kama Sutra moves and a confidence in his own inanity.

Though Aldous Snow may be vain and nonsensical, he is also terribly funny and rather likeable - much like Brand.

Reviews of the film in the States have unanimously praised his "oddly insinuating charm", and even the unlikely publication Christianity Today lauds his "subtly hilarious way with ... oddball dialogue".

It's true you want to play approximations of yourself initially," he says.

"I don't plan on transforming like Daniel Day-Lewis. I'd like to just carry on like this for a while to let them know who I am."

Did he find the Americans puritanical about sex? "No. I found them to be confident, comfortable - and willing," he smiles knowingly.

It says a great deal about Brand's persuasive charm that, though the original idea was to have his character be an author with Hugh Grant-esque foppish qualities, after auditioning Brand, the producers turned his character into a rock star with Russell Brand-like qualities.

"They were incredibly generous and gave me a lot of freedom," he admits.

"They allowed me to improvise lines which was liberating for me because as a stand-up comedian I'm happier when I'm writing my own material.

"It was like being a spoiled, precocious and indulged child. Everything I said was applauded and celebrated."

Like his screen character, Brand is sporting a serious amount of eyeliner, and in spray-on trousers and black shirt, with his just-got-out-of-a-flowerbed hair in a state of dishevelment, he looks as though he might have sauntered into his Los Angeles hotel straight from the movie set.

Though most actors would have relished the two-month filming schedule in Hawaii, Brand admits his stay was fraught with difficulties, beset, as he was, with the dual complexities of learning to ride and surf while keeping his hair just so.

"I don't go to the beach, as my hair does not mix well with maritime matters and when I had to do a surfer scene in the film, I had to employ every technique I've ever learned to stop myself weeping for a hairdresser.

"When it came to horse riding, that was hard, too, as it was my first time. They were saying 'Oh, do it like you're driving a car', but I can't drive a car.

"Also, when you're driving a car, the car doesn't of its own volition wander into a garage and demand food and start eating it. How can I be in the lead in that relationship?

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But I enjoyed my time enormously, even though I missed my life, my cat, my home.

"I really like LA - I'd heard it was a superficial and vacuous space and astonishingly, I fit right in."

Though he may be only half-joking, there is no masking his ambition to make it big in the States.

He has been performing stand-up gigs quietly and to small audiences in LA, "I know, though, that I'm a different phenomenon and I plan to exploit that by being ludicrously English - but I'll speak slowly."

Though his film career may be in its infancy - his other most notable role was opposite Colin Firth and Rupert Everett in last year's St Trinian's which opened to mixed reviews - it is as a stand-up comedian and radio and TV presenter that he is primarily known.

His two-hour digital music show transferred from BBC6 to Radio 2 amid much hubbub two years ago and his hosting of the Big Brother spin-off, Big Brother's Big Mouth, brought him an even wider audience.

However, it is for his stand-up, and by extension his personal life, for which he is known in Britain, and whether his life fuels his art or vice versa is hard to determine.

It remains to be seen whether his frequent picaresque exploits will go down as well in the conservative States.

This was the man, after all, who boasted at an awards ceremony that he had bedded Rod Stewart's daughter Kimberly, only for a seething Rod, himself a member of the audience, to demand that the sheepish-looking Brand stand up in front of everyone and apologise for his remarks.

"What doesn't change is the incessant and relentless embarrassment that pursues me everywhere," says Brand.

"My stand-up is defined by being an honest and confessional examination of what it is to be alive and how embarrassing that can be, how funny that can be, and how sexy the whole thing is."

Of his co-star, Kristen Bell, Brand says matter-of-factly: "I'm annoyed I didn't get to be naked with Kristen Bell.

"I'm very comfortable with her now. We did some sex scenes together but they were awkward, embarrassing, disappointing and expensive."

At times one wonders whether Brand isn't too honest and confessional.

At 37, he has already published a bestselling autobiography, detailing his descent into heroin and crack cocaine addictions, his sexually compulsive behaviour (he lists Kate Moss and assorted Big Brother alumni as some of his many conquests) and at the root of it all, his horribly troubled childhood.

His father left home before he was a year old and his mother was diagnosed with cancer.

Added to that, he suffered bulimia and was a self-harmer, and in his most candid confession, revealed he had been abused as a child by a neighbour.

That he should have entered adulthood, therefore, with more than a little streak of self-destructiveness in him is entirely understandable.

Starring role: Russell is hoping Forgetting Sarah Marshall will give him his Hollywood break

Born in Grays, Essex, the only child of Barbara and Ronald Brand, the young Russell had a difficult time from the start.

With a dad who "played the role of the absent but somehow glamorous non-maintenance-paying father" and a mother who worked many jobs to make ends meet, Russell, an "effervescent, attention-seeking, fizzy ball of emotion", was at times a self-confessed loner.

His mother, to whom he remains devoted, suffered three bouts of cancer (the first when Russell was eight) and as he admits: "At the back of my mind I couldn't stop thinking that if someone keeps getting cancer, they're going to die.

"In some sense I'd made the decision that she, the person who'd been the constant reference point in my life, just wasn't going to be around any more. And all those thoughts, well, it was too much."

He had a difficult relationship with his stepfather, who was "goodlooking, with all those masculine energies, just sitting around, drinking lager, dominating the sitting room" and as he became increasingly isolated, depressed and overweight, Russell took to binge-eating and vomiting and, later, cutting himself.

He was abused by a neighbour as a child, and although he told his parents and never had any dealings with him again, no formal charges were ever pressed on his abuser.

With all this going on, it was perhaps understandable that the teenage Brand sought escape in the form of drug-taking, and as he admits: "By now, I was of the attitude that all life was painful and miserable, so why not take drugs?"

What saved Brand from self-destruction was a role in the school production of Bugsy Malone when he was 15.

It was then he discovered a love of performing, and after winning places at the Italia Conti stage school and the Camden Drama Centre (he was expelled from both for disruptive behaviour), he had found his passion.

Inspired by his comedy idols - Eddie Izzard and Reeves and Mortimer - Brand tried his hand at stand-up, going on to be named Time Out's Stand-Up Comedian Of The Year in 2006.

With his reputation burgeoning, he fronted several shows on MTV until he was sacked in 2001.

He was then sacked from his Xfm radio show for reading out pornographic letters on air, and rather more politely released from his role in the Steve Coogan comedy Cruise Of The Gods.

His erratic behaviour and stalling career were not being helped by his dangerous addiction to drugs, and it was thanks to the intervention of his agent, John Noel, who sent him for treatment at the rehab facility, Focus 12, that Brand finally started to pick himself up.

"They analysed me and said: 'If you don't stop taking drugs now, you'll be dead, in a mental asylum, or in prison within six months.'"

Brand has been clean for six years and is a patron of the rehab facility that helped save his life.

Though his battle against drug addiction may have been beaten, his other well-known addiction - to sex - appears still to be full-blown, and he revels in his promiscuity, declaring: "Monogamy isn't necessary. I don't even know if it's a good idea.

"I could have a harem situation, like you do in certain tribes on our planet."

Others, needless to say, haven't been too comfortable with Brand's brand of sexuality.

Dannii Minogue once labelled him a "vile predator", an accusation which rankled as he replied: "If that's the language you're going to use about someone who really ought to be described as 'having a bit of an eye for the ladies', then what sort of language are you left with for Peter Sutcliffe?"

And although he is the frequent target of kiss-and-tells, he bears the burden with commendable good humour.

"One kiss-and-tell story said: 'He's unusual. He wore slippers in the house and talked to his cat. When we got in, there was a bowl of cat food on the floor.' Well, where else do you put cat food?" he says.

It remains to be seen whether Brand's humour will translate well across the Atlantic, but he is lined up to do another film with Judd Apatow (the man behind Forgetting Sarah Marshall) and is filming Bedtime Stories, a comedy featuring Adam Sandler.

"I'm his psychic, called Mickey," he burbles.

"I mean, a character called Mickey in a Disney film - isn't that a wonderful name? I'm so excited about that."