There is a remarkable consensus among theatre people―from directors to critics to audiences―that the 32-year-old actress Victoria Hamilton is the Judi Dench of her generation. What they mean is that her grounding is in stage acting, she’s worn her fair share of corsets, she's on the short side, and, though striking, is not a conventional beauty. They also mean that she is a good actress, a commandingly good one.

The big stage directors, in particular, love Hamilton. When Richard Eyre, for example, was filming King Lear with Ian Holm and needed a Cordelia in a hurry, Hamilton was the first person he thought of. In fact, at the time she was playing the same role for Peter Hall at the Old Vic. At the National Theatre under Trevor Nunn she appeared in Summerfolk and Money. Sam Mendes wanted her to join the cast for his farewell Donmar productions of Twelfth Night and Uncle Vanya (she turned him down to go to Broadway with the hit production of Peter Nichols’ A Day in the Death of Joe Egg).

She won a Critics' Circle award for her performance as Rosalind in Michael Grandage’s feted As You Like It at the Sheffield Crucible in 2000. “It was absolutely extraordinary, that experience,” she says, and her dark brown eyes stretch at the memory. “An awful lot of it I’m sure is to do with Michael. That entire company felt like they were on E for three months.” No wonder she’s looking forward to returning to Sheffield to play Catherine in Grandage’s new production of Tennessee Williams's Suddenly Last Summer.

But first there’s Sweet Panic, written and directed by Stephen Poliakoff, which opens in the West End next week. Hamilton plays Clare, a child psychologist who finds herself more or less stalked by Mrs Trevel (Jane Horrocks), the brittle mother of one of her patients.

The piece is a typically rich Poliakoff confection―mixing elements of a psychological thriller with a play about the state of London at the turn of the Millennium, as well as incorporating a debate about the damage our accelerating culture inflicts on children. Mrs Trevel embodies the middle-class anxiety that our children are growing up too fast, while Clare argues that there is no call for panic, as things are no better or worse than they used to be.

“The role is a whacker,” says Hamilton, sipping from a glass of white wine after rehearsal. She is in nearly every scene, and is also required to do the voices of the children she counsels. It sounds, I suggest, like a terrific chance to turn great actorly cartwheels all night. “Of course it’s a cartwheel,” she concedes. “But the only reason it's a great cartwheel instead of a bollocks cartwheel is that you've actually got a fantastically intelligent script behind you.”

The role could be seen as a telling progression from the one she played in Joe Egg, that of the mother of a child with cerebral palsy. “I really hadn’t made the link, but one of the weird things I’ve had to get my head round for the last two years is I’ve finally started being cast as a mum. It’s a very strange thing the first time you get cast as a mother when you’re not. I’m not,” says the currently single Hamilton, “going to be a mum in the foreseeable future. I’m sure Joe Egg was one of the reasons why playing this role is sitting easier with me now than it would have been three years ago.”

Another thing that’s changed is that Hamilton is well on the way to West End stardom. Two years ago, when she opened in Joe Egg, she was much less well known than either of her co-stars, first Clive Owen and then Eddie Izzard. With Izzard the production took wing and fetched up earlier this year in New York.

“It was fantastic, the fact that we got there, because no one has got a clue who I am and you have to be someone to be on Broadway. There is that very American take that if you are in a hit you should celebrate it. People that you don’t know will knock on your dressing-room door after the show. In one day I had lunch with Antonio Banderas, met Meryl Streep―Meryl Streep!―and then went to dinner with Lauren Bacall.”

As her stock has risen, Hamilton has resisted the crescendo of whispers in her ear advising her to park herself in Hollywood and see what happens. “When you talk about the American film market, ninety percent of it is, ‘Do you look like Cameron Diaz?’ Well, I don’t. I’m not that sort of beauty. I’m just not. I’ve been told I’ve got a Jane Austen face. It’s basically a round face with big eyes, a fairly demure-looking face.”

This would explain why she was every inch the saucy young Queen in the BBC's recent Victoria and Albert, and before that in no fewer than three of the Jane Austen adaptations in the 1990s―Persuasion and Pride and Prejudice on television, and Mansfield Park on film. Hamilton’s appearance in the latter is the only recorded instance of an Austen character actually being seen to be a slapper. Her Miss Bertram was caught in flagrante delicto with Alessandro Nivola.

Hamilton flinches. “Yes, it was genuinely shocking. It was quite shocking for me as well. It was one of those ‘I was very young and I needed the money’ things, I think. We’ll leave that one at that,” she says. Then she adds, “There were things about the movie that were great and things that maybe didn’t gel quite as much as they should have done. The Austenites were hugely angry that they actually saw anyone take off their clothes. But that was going on under that roof. And that director chose to show it.”

Hamilton, who had been planning to read English literature at Bristol, discovered she wanted to act after two National Theatre actors visited the private school she attended in Surrey. “I don't think I had a choice but, when it’s nowhere in your family and you don’t know anyone that does it, even though there is no question about it, actually saying the words is very difficult.”

After training at LAMDA, she determined to do only classical theatre, “because if you crack that you can do pretty much anything. If it is possible to guarantee any kind of longevity in this business, you have to be as good on-stage as you are on film and TV.”

Thus, in her mid-20s she ended up at the Shakespearean finishing school that was the Peter Hall Company. And yet she was miserable playing Cordelia. “I was adhering so much to his rules that my own performance went out of the window. He kept saying that eventually the rules would just seep in. But with me it took another five years, which I’m glad I did. I learnt an awful lot but you then have to move on. You have to take what works for you. And get rid of the rest.”

It seems she learnt just as much from Izzard. “I think we filled in the gaps in each other's acting. I had the technique, because he hasn't done as much stage work. He kept saying, ‘Tell me if this is right, tell me if that is wrong.’ He taught me to dare a lot more on-stage, which you can only do when you are working with someone you trust absolutely. He gave me that back. I hope we gave each other equal amounts. I think we did.”

Their double act was cheered by the critics and the public, and both were nominated for Tonys. “There is always a bit of you that goes, wouldn’t it be great to win a Tony? Winning awards is great. Everyone's lying if they say it’s not. It is. We're all insecure and all of you want your peer group to go, yes, you actually can do this. But I have to say there was a bit of me going, dear God, please don’t let me win because I’m actually not ready to get up on the stage in Radio City in front of all these people and be witty. It sounds like a line. But that’s how I felt. Don’t let it be me. Not now. Not today.”

And it's a tribute to her talent that, while she spoke those lines, I actually believed her.

Clearly I’m not glamorous, Hollywood kind of material. I’ve got tits and a bum and I’m happy about that. I don’t like being thin, I don’t feel well or sexy when I’m thin. I went through a phase about five years ago where I was paranoid about my weight. I was never anorexic or anything like that but I ate a lot less and was down to around seven and half stone which made me feel terrible, I had no energy. The industry wants you to be thin and glamorous and there’s an incredible pressure to adhere to a certain set of rules. It’s very rare that a very big, buxom girl will get cast as a female lead. I have huge respect for actresses of my generation who’ve basically told that side of the business to sod off, but when you know that if you were a stone lighter you’d be offered parts, it’s very tempting and very dangerous. I reached a point where I thought about the kind of career I wanted, and realised I didn’t want to be a sex object, I just wanted to look like me, which is OK one minute and then like hell the next. But I’d much rather look like that and be real than make myself miserable trying to conform to some kind of 6ft 2in, long- legged, no-breasted stereotype.

When you tell people you’re an actor they immediately assume you're hugely confident, possibly rather arrogant and almost inevitably very vain. I’m not. Sometimes, on set, they’ll say to you, ‘Right, you have to look shit at this point’ and it's a huge relief. You’ve been told you can look terrible and you genuinely don’t have to care. One of the parts I enjoyed playing the most was a drug addict who’d been travelling round India selling her body to people and arrived back in England looking awful. I loved it. Instead of sitting in front of the mirror every night before curtain up trying to make myself look more attractive than I really am, I just had to fill my hair full of grease and mud and then all I had to concentrate on was the acting.

When I played Queen Victoria I had to look a lot fatter and jowlier as the years went by and it was very weird seeing myself age like that. Having 40 years put on you is an extraordinary feeling and very unnatural―nobody should be confronted with what they’re actually going to look like without having years to gradually get used to it! I’ve played a lot of period dramas―apparently I’ve got a period face, whatever that means. Small features, big eyes and something that would suit a wig I suppose. Casting directors or agents always describe me as elfin or gamine. I don’t think of myself as like that but after you hear it again and again you do actually start seeing yourself as others see you.

I’ve always really liked being dark―I think it suits my personality much better and it’s great for the stage. If you’ve got dark hair and dark eyebrows it’s the simple fact that from far away people can see more expression on your face than they can if you’re very, very blonde. I did go blonde once for a job and people, men, treated me differently which was fascinating. They seemed to find me much more approachable.

I’ve only ever done one nude scene, for Mansfield Park, which was just hysterically funny. I was very nervous about it and drank half a bottle of wine in my trailer beforehand. It’s a very strange thing because for a few hours before you do it everyone starts treating you with kid gloves, which of course makes everything worse. There was a series of bangings on the trailer door―first somebody stuck their head round and asked “Do you require body make-up?” and then another came in and said, “Do you need to be gaffered?” I was really at a loss then. What she was asking was did I want gaffer tape stuck over my bikini area. I thought―what’s going to make you feel more of an idiot? Walking into a room and taking your clothes off, or walking into a room and taking your clothes off, all but a yellow, luminous piece of gaffer tape. Apart from anything else imagine the pain getting it off. My God, you'd give yourself a ‘Brazilian’!