Ben Whishaw trundles in with a black rucksack clutched in his hands. Removing a 10-pack of Lucky Strikes from his bag, he slumps in his chair as if he's just arrived for a particularly tedious college lecture. In fact, with his black jeans, chunky navy cardigan and light blue T-shirt, the first thing you think is: student . It hardly helps that, located in a plush hotel in London's Piccadilly, Whishaw looks as if he could barely afford a bottle of still water from the menu. In the end, he chooses a coffee, swimming with milk, and blazes up the first of several cigarettes, cradling it as if it's his only friend in the world. Quite an introduction, you might think, to Britain's brightest young acting talent.

Such a weighty reputation stems from one role alone. Back in May 2004, when Whishaw was 23, he was cast as Hamlet in Trevor Nunn's celebrated production at the Old Vic. With his willowy frame, pallid complexion and thoughtful look in his bright blue eyes, Whishaw was evidently born to play Shakespeare's Dane. At the time, Nunn had announced that he wanted to cast a genuinely young man in the part, a move initially greeted with scepticism from the critics. "What made it kind of joyful was the fact that I was inexperienced and nobody knew who I was, so there was no pressure," says Whishaw. "It felt quite uncomplicated playing it."

To be fair, he wasn't a complete unknown. In 2001, Whishaw won Most Promising Newcomer at the British Independent Film Awards for the low-budget film My Brother Tom. But when he arrived on stage, complete with beanie cap, he was hailed as a new discovery and compared to the likes of Richard Burton, Laurence Olivier and Peter O'Toole. "Whishaw with his light, tremulous voice, painfully thin body, and the kind of cheekbones that will have adolescent girls swooning in the stalls, presents the most raw and vulnerable Hamlet I have ever seen," gushed The Daily Telegraph's Charles Spencer. Or as commentator Paul Morley put it delicately on BBC2's Newsnight Review, "I do think he is the erection in these trousers."

Today, he's not quite so, well, stiff. Rather, he's a bag of nerves. Placing his cardigan on the back of his chair, Whishaw rolls up the right sleeve of his T-shirt so it rests on his shoulder and begins to fiddle with the wooden bracelet around his wrist. A whirr of expressive animation when he speaks, his hands acting out his words, his intense gaze rests either on the ceiling, the table below or, arrow-like, in front of him; rarely will you be greeted with the luxury of eye contact. To some, this must be torture, for with his dark quiff-like mane of hair, ragged cheekbones and pencil-thin stubble on his top-lip, it's impossible to take your eyes off him.

It strikes me he'd be more relaxed if there was a two-way mirror between us, emulating the "fourth wall" of the stage. Perhaps this is why he acts: it's the only way he can be free of feeling self-conscious when all eyes are upon him. It's clear he still hasn't really adjusted to the accolades. "Doing the Hamlet production I mean obviously I knew people reviewed plays, but I had no idea of the impact or importance," he says, a naïve trill ringing in his voice. "It still felt quite an innocent thing to me then. It was just playing; it's the thing I've always done. Now I'm much more aware of all the baggage that comes with it - which is not always nice baggage - but you try and keep your head down and not to be too distracted by it."

By baggage he means "expectations", as the artistic community wondered where he would tread next.

"It's probably paranoia on my part, but people love to lift you up and then knock you down, which is a very British thing," he says. "I'm aware of that." As it was, Whishaw played it smart. Snapped up to play Sienna Miller's cuckolded boyfriend in Matthew Vaughn's gangster thriller Layer Cake, he followed it with an equally brief appearance as a young Keith Richards in Stoned, which told of the demise of fellow Rolling Stone Brian Jones. Whishaw excelled as the cool-but-cruel Richards, but maintains he did it because he needed to shift down gears after Hamlet. "I wanted to do something that didn't require tearing your heart out for three hours."

Meanwhile, on television he won a small role in Brass Eye creator Chris Morris' Hoxton-set media sitcom Nathan Barley. He played the picked-on Pingu (passers-by still shout the name at him in the street, he says). "I had no clue what it was we were making because Chris is extremely secretive, even with the actors he's working with," he recalls. "I had never done comedy like that before - I don't consider it my thing - so the pressure was off in a way and I could just kind of enjoy it." Likewise, on stage, he played in Philip Ridley's Mercury Fur, a disturbing vision of a violent future which he says was appealing because it felt "unexpected" after Hamlet.

Whishaw's only lapse might have been his turn as Konstantin in Katie Mitchell's production of Chekhov's The Seagull this summer at the National Theatre. Certainly, it's no imaginative leap from the Dane to Chekhov's creation; both, according to Whishaw, are "hypersensitive mummy's boys" and "very bad news for the young women they fall in love with". He admits he was concerned about repeating himself. "I did question whether it was the right thing to do, just because I think most actors live in fear of being typecast as something, and if you start typecasting yourself or putting yourself in a bracket, then that's even more horrific."

In this regard, it's curious to note that for his first major film lead he has chosen another outsider, one who is most certainly bad news for the women he fixates upon. Still, there's no doubt he's perfect casting for Perfume: The Story Of A Murderer, a luminous adaptation of Patrick Süskind's bestselling 1985 novel. Whishaw plays the 18th-century Parisian orphan Jean-Baptiste Grenouille, a child who develops a highly attuned sense of smell, while possessing no bodily scent of his own. Under the tutelage of a one-time successful parfumier Giuseppe Baldini (played by Dustin Hoffman), he begins to put his unusual skill to work - until he becomes obsessed with creating the perfect scent, a plan that can only come to fruition by killing a series of women and extracting their smell.

Given the difficulty of conveying smells for the silver screen, German filmmaker Tom Tykwer (best known for Run Lola Run) does a remarkable job in bringing to life what might be considered an unfilmable novel. It positively reeks, from the rotting stench of the fish market where Grenouille is born, to the luxurious aroma of the perfumes he creates, in what must be one of the most sensuous experiences ever committed to film. Tykwer, who had seen Whishaw in Hamlet, credits his leading man for helping channel this. "It was probably the most beautiful and exciting actor-director relationship I've ever had," he says. "He's one of those actors that can work on a super-intuitive and instinctive level. At the same time, he's intellectually capable of any kind of conceptual talk."

Whishaw certainly has a grasp of his character, who has been more neutralised (he was a hunchback with a gammy leg in the book) on screen. "I think of him as pretty amoral," he admits. "I see him as an artist and a kind of Everyman - somebody hopefully an audience can recognise elements of themselves in, even though he's deeply odd in many respects." Whishaw denies he's playing a simple killer, though. "I don't think he is sadistic at all. It's for a greater end - he's not getting any thrill out of the act of murder. He's much more innocent, really. There's something pure about him. There's an animal urge or instinct, which he doesn't understand because he's not an intellectual being. There's something in his gut that's driving him on, and that's what we were interested in exploring."

Not unsurprisingly, Whishaw became consumed by a role that deals with obsession. "Film for me is quite new territory anyway - it's not something I'm so familiar with - and I was a bit obsessed with getting it absolutely right, and sometimes that is an inhibiting way of working, if you're struggling to do something correctly." The knowledge he was shouldering a major European production gnawed at him to the point where he became physically ill with stomach cramps before the shoot. "I remember being very, very conscious of those pressures to begin with, but they hinder you," he says. "You have to be brave. It's not a creative way to exist if you let it impact upon you too much. That's what I learned from Dustin; that it's okay to fail occasionally."

But while Hoffman's scenes were filmed near the beginning of the shoot, Whishaw was then left alone on screen. "Ben has so many scenes with himself," confirms Tykwer. "There were days and days and days where we were just shooting him and dead bodies!" Playing such an isolated figure that barely speaks, Whishaw admits it drove him to distraction. "It did start to get to me for some reason just 'cos usually acting is so much about sharing, listening, observing and bouncing off people - and there was relatively little of that. I turned inwards, which was necessary - because the character is an inwards-focused person - but I did find two-thirds of the way in it started to addle my brain."

At this point, he manages to nudge his ashtray, sending a cloud of dust billowing over the table. "Look at the mess I've created," he groans, and proceeds to scrape bits off the table. Satisfied with his clean-up job, he tells me his sense of smell has become more attuned since the shoot. "This film did make me more aware of it. I do sometimes now stop and enjoy a smell, depending on what it is." Does he experience, as so many do, certain scents bringing back old memories? "I always find the smell of detergent that they clean schools with, a really pungent overwhelming smell, takes me right back to being a kid. They obviously use the same stuff all over the country, because whatever school you pass just reeks"

Being reminded of your school days is probably something Whishaw would rather avoid. Born and raised in Bedfordshire with his twin brother James, it seems Whishaw, a self-described "oddball", did not fit in well. "I was quite quiet, really," he says. "I didn't really like school very much, but I tried to find a way of getting what I wanted out of it. So, yeah, I wasn't very interested in a lot of what they were trying to teach us." He disliked maths, science and geography, he says. And sport? "No, my brother got that gene. I'm pretty hopeless to be honest." Painting was his only joy. "I loved the art room - I felt at home there. It was a good space."

It comes as no surprise to learn that when he left school, Whishaw enrolled in an art course, though he quit after a month, because he kept bunking off to go and watch various Samuel Beckett plays at a Barbican season. He had been interested in acting ever since he was a child, when he used to put on plays and act out stories and characters. He doesn't know where it comes from. His mother sells cosmetics while his father "does something with computers - I'm not really sure what it is". But he says they were "strangely" encouraging of his passion, even though "they're not theatre people or involved in the arts in any way at all".

After joining a local youth theatre, he secured an agent when he was 14, and three years later was spotted by William Boyd for his first world war film The Trench, alongside Daniel Craig (with whom he reunited on Enduring Love and Layer Cake). A year later he took on My Brother Tom, an intense story of two abused teenagers, but rather than focus on film after that, he decided to take the classical route and apply for drama school. Accepted at Rada, he admits he's "thrilled" he got the chance. "I just think it's great to be a student and not have any pressure. You can explore yourself, can't you? I'm really grateful for having that experience."

Pressure: it's a word that seems to have come up numerous times today. Whishaw seems all too aware of outside factors working upon him right now. Does he think about the prospect of fame? "I really, really try not to, because it just frightens me. You can't go through the world completely unaware of it, but I just try and stick to my guns and do the things that turn me on." He cites I'm Not There, the Bob Dylan film he has just completed for Todd Haynes, the American director of Velvet Goldmine and Far From Heaven. "I love the music," he says. "That was one of the things that interested me - that's my period. I loved what was happening then. It seemed so much more interesting than what's happening now."

Alongside such diverse talents as Heath Ledger, Christian Bale and Cate Blanchett, Whishaw is one of seven actors playing "aspects" of Dylan. "It's not a traditional biopic at all," he explains, noting his character is a "hybrid" of Dylan and the poet who so influenced him, Arthur Rimbaud. "It's much more about facets of his personality and the different ways he reinvented himself. The thing you forget about Dylan you look at the films of when he first came about, when he was 19, and he was still a boy, even though he was writing these extraordinarily complex and wise sort of songs." Calling it "brave and strange" - two words that rather sum up Whishaw - he assures me it "doesn't feel like a Hollywood film at all".

Such notions seem important to Whishaw, who seems sensitive to how he is perceived. A London resident for six years, he currently lives in the actor-magnet suburb of Muswell Hill. "I live in the scummy bit," he protests, as if to distance himself. "Right by the North Circular." I wonder if the idea of relocating to Los Angeles is not high on the agenda. "Just the idea of it in itself is not especially appealing. I don't think I'd get on particularly well, or feel particularly comfortable. I just don't think as a personality I would fit in there. I don't feel I could give them what they wanted. I'm not interested in it. It's fine for people if they want it, but it's not for me."

This Bedfordshire boy seems too fragile for the fickle world of Hollywood; doubtless he'd feel just as much of an outsider there as he did at school or on stage. Currently, he's nervously sitting out a hiatus on The Restraint Of Beasts, the new film from Pawel Pawlikowski, who made My Summer Of Love. The film has been halted for "complicated" reasons, according to Whishaw. Even if it restarts, unemployment looms afterwards. "I've got nothing to go on to next, and if nothing came along, then I'd think about what else I might do. I just think I'm grateful for the work I've had so far, and if nothing else comes along, then so be it."

Perfume: The Story Of A Murderer opens December 26