Not too Posh to push the envelope

RONNI Ancona's most famous alter ego, Victoria 'Posh' Beckham, is said to be very relaxed about being impersonated by the star of BBC1's The Big Impression. According to Ancona, "I've never met Posh, but I've heard through the grapevine that she and David haven't got a problem with us. They've got a sense of humour."

But Ancona feels that there has been a downside to the success of The Big Impression, in which she and her ex, Alistair McGowan, have starred since 1999, and during which she has memorably "done" characters as varied as Nancy Dell'Olio, Madonna, Angelina Jolie, Sarah Jessica Parker, Sharon Osbourne, Ruby Wax, Penelope Cruz and Sporty Spice.

"Alistair and I were both trained as actors, but you can get sucked into a vortex where, before you know it, you're stuck in a box," says the Scottish performer. "That's happened to me. It really doesn't matter what else I do, I'm still 'the girl who does Posh'. I've done everything from playing Liz Taylor running an estate agent's to Audrey Hepburn serving in a burger van, and I'm still only known for Posh. It's one of the impressions I've done least. But I still don't even get my own box - it's deeply frustrating."

Over the past couple of years, Ancona has certainly been doing her best to avoid that fate by taking on a variety of dramatic roles, including her latest, in Stephen Poliakoff's poignant new BBC1 film, Gideon's Daughter.

The actress is an engaging bag of neuroses. She is successful and beautiful; described by one journalist as "comely in a Nigella-esque, Jewish sex-bomb way".

Nevertheless, Ancona is constantly assailed by self-doubt. At one point, she recalls that before becoming a performer she used to teach A-Level Technology to frighteningly self-confident students. "They had a self-assurance that I won't have when I'm 70," she says. She also laments: "I'm not totty, and I've never made one of those lads' mag lists. I don't even qualify for thinking man's crumpet. Not Carol Vorderman enough, I suppose."

But that lack of braggadocio is actually what makes Ancona so appealing. Unlike a lot of more vain, self-regarding actors, she finds it impossible to conceal her vulnerability. She goes so far as to cultivate the image of a terminal flibbertigibbet. "Don't mind me," she says, "I'm completely scatty. Really, I'm quite mad."

Ancona's sense of humour is currently being sorely tested, however, by the industry's insistence on pigeon-holing her as a "mere" impressionist. "Being part of something that has done very well hinders you in some ways because there are preconceptions about what you can do," she says.

"People say, 'she just does comedy skits', and that doesn't help. They come with preconceived ideas. Alistair has suffered from the same thing. When he does straight acting, people say 'oh, that sounds like such and such an impression.' Because I do lots of voices, can't they just say I'm a versatile actress?"

Ancona is especially fed up with critics who cavil that "if you're doing impressions, you're not acting". "Try telling that to Cate Blanchett [who played Katherine Hepburn in The Aviator] or Jamie Foxx [Ray Charles in Ray]. Not that I'm in the same league as them," she adds hastily, that insecurity gene kicking in again.

"And exactly what was Anthony Hopkins doing in Nixon, if not an impression?" asks Ancona, who has headlined in notable straight dramas such as The Key, The Calcium Kid, The Debt Collector and Singin' in the Rain, and late last year starred as the scheming gold-digger Belline in the acclaimed production of Moliere's The Hypochondriac at the Almeida in London.

Working up a head of steam, Ancona says: "I don't approach comedy or drama any differently. As soon as you think, 'Oh I'm doing comedy now,' you're on to a loser. Whatever you're doing, you have to make it live and breathe. Whether you're playing Posh and Becks or Lady Macbeth, the key thing is to create something believable. You have to find the reality and truly inhabit the character. If viewers can't identify with what you're doing, it's never going to work."

The actress is delighted that more enlightened directors don't view her as laden with that baggage. "It's very interesting that very eminent directors like Stephen Poliakoff and David Blair [the Scottish filmmaker responsible for The Key] don't have a problem with my background. I went up for a long audition for Gideon's Daughter, and Stephen didn't have any preconceptions about me at all because he's a true artist and open to everything."

HIS FAITH PAID off. In Gideon's Daughter, Ancona delivers a mature and nuanced performance as Barbara, a "media bitch" in love with the intoxicating, yet vapid realm of first nights and red carpets. In this film, set against the backdrop of New Labour's election victory of 1997, she is the apparently brittle girlfriend of Gideon (Bill Nighy), a government PR guru charged with attempting to sell the concept of the Millennium Dome - the ultimate symbol of New Labour spin.

Barbara, however, is so wrapped up in herself that she fails to notice that Gideon is having a breakdown, precipitated by the vacuity of the media universe over which he presides.

The drama has many trenchant things to say about New Labour's obsession with style over substance. Ancona says: "This will be the definitive film about the Nineties. It shows how much of that decade was like the Emperor's New Clothes."

The 37-year-old Ancona, whose father was in the Navy and who has two brothers, grew up in Troon - "a lovely place, but if you don't like golf, forget it". After school, she did a degree in design at St Martin's in London.

She went on teach, before becoming a tour guide. It was during this job that she discovered her talent for mimicry; she would entertain American holiday-makers with her impersonations of Marilyn Monroe, Bette Davis and Shirley Temple.

Realising that she could make people laugh, she spent the next decade on the comedy circuit. In 1993, she picked up both the Time Out Award for Best Stand Up and the Hackney Empire Newcomer of the Year Award, and later supported Rory Bremner on tour.

They were frequently tough times. She says: "I don't go in pubs much these days because they remind me of humiliation from my stand-up days." But everything changed when in 1999 she and McGowan were spotted on the circuit and commissioned to make The Big Impression for BBC1.

Ancona now lives in Notting Hill, West London, and is married to Gerard Hall, a doctor at the Royal London Hospital. They have a nine-month-old daughter, Lily. She has proved a natural at motherhood and is clearly devoted to Lily. "Thank goodness for my daughter," she says. "She gives me a perspective. Her safety is the only thing that matters. I just think that as long as I could get between the car and the pram I have my priorities right."

At the same time, the actress is keenly aware that in her game you can't stay out of the limelight too long. "I love Lily to death, but I'm the type of person who will always need to work - otherwise I'll drive everyone mad," Ancona says.

To that end, Ancona has quite a few projects in the pipeline. She will be starring opposite Dexter Fletcher and Jenny Agutter in In Your Dreams, a new movie from Gary Sinyor (The Bachelor, Leon the Pig Farmer) about a dentist who finds that dreams come true. The actress is also planning to work again with McGowan in the near future. "We haven't stopped collaborating," Ancona says. "We still want to do other things together. We're addicted to working with each other. It's a horribly volatile relationship in that 'can't live with you, can't live without you' kind of way.

"We have the most appalling rows, but we drive each other creatively and you develop a genuine chemistry when you work with someone for such a long time. It's very hard to break away from that because you really enjoy the challenge of pushing it."

Their sole concern is finding a new angle. "For us, there's no point in doing impressions unless you've got something to say," Ancona says. "There is a lot of impressionism around, and we don't want just to recycle old ideas."

The omens are good, though; the pair have always had their finger on the pulse. "When we started seven years ago, we did a lot of TV parodies, and now they've all happened for real. We did Changing Faces, a sort of extreme makeover show, and Celebrity Wife Swap, and they've both happened. You can't parody some programmes."

Ancona still gets a major kick out of residing in the skin - and voice - of other people. To underline the point, she has been on the receiving end of the highest accolade from some of her "targets".

"Carol Smillie, for example, loves it," Ancona says. "She's even started using the catchphrase I gave her - 'Smiley, Smiley Carol Smillie'. That's the ultimate compliment."

Ancona just has one plea for everyone looking forward to a revival of The Big Impression. "I don't want to go to my grave as 'the girl who does Posh'. Please."

• Gideon's Daughter, Sunday February 26, BBC1, 9pm