Kate's dullard secretary is droning on about new ways of improving efficiency in the office. Kate, unable to take any more, butts in: "Let me stop you right there." "Yes?" says the secretary. "Nothing. Just let me stop you right there."

Caroline Quentin was born to play the title role in BBC1's new sitcom, Kiss Me Kate. She brings to the party all those (polite) F words: feisty, firm, flirty and, oh yes, funny.

She has come a long way since her "big break" in showbiz at the age of 16 when she played a none-too starry role in a seaside variety-show in Lowestoft - "I was one of those girls who stand in the background with sparkly bikinis on."

Now she's the one doing the sparkling. Leading roles in two of BBC1's ratings bankers, Men Behaving Badly and Jonathan Creek, have given Quentin the sort of clout that has channel controllers phoning her with the regularity of England fans trying to secure World Cup tickets on the French hotline.

Nick Symons, her producer on Kiss Me Kate, gives a typical example of the industry infatuation with her. "Put simply, she's a star," he raves.

Tailed wherever she goes by an adorable black-and-white dog called Ollie, and dressed in a natty dinner-jackety black trouser suit, Quentin sends off more sparks than a steelworks.

But for her, the best aspect of stardom is that, finally, sisters are doing it for themselves. "With Kiss Me Kate, I liked the idea of a woman being the central figure in a sitcom. Dawn [French] and Jennifer [Saunders] have done it with The Vicar of Dibley and Absolutely Fabulous, but it's still quite rare. It's been by men, for men, for a long time, but that's changing now. America has shown the way ahead with series like I Love Lucy and Ellen. The way forward here is giving a woman the responsibility to carry a series."

It was not ever thus. "In the past, it was the same old story of commissioning editors thinking `Women aren't funny. They can't be foolish and an attractive person at the same time.' We preferred our central female characters to be men dressed up as women."

Not anymore. An independent-minded thirtysomething with her own business, Kate also happens to be single - and is quite happy about it. She doesn't feel defined by her lack of a partner. "I like the fact that she's not in a domestic situation. Unlike a lot of sitcom characters, she has no husband or boyfriend. She's smart without being unfeeling, and she can empathise while still managing to be independent."

But for all her upbeat view about the new series, Quentin knows that an actress of her profile can all too easily fall victim to scythe-wielding critics anxious to cut down a "tall poppy". "The backlash is bound to happen. I've had a good couple of months, so I deserve a slap."

Kate's job is counselling, and the sitcom is not without its darker moments. "I like things that have both comedy and drama in them. No comedy that's not based in reality is funny, and no drama without humour is true. My sister, Hazel, has been an HIV counsellor for five years, and even there people find humour. Even at the grimmest moments, when human beings are at their lowest ebb, there are laughs. That's why Chekhov and Ibsen are so great. They understand that."

Quentin's two most celebrated works share that mingling of light and shade. At its heart, Jonathan Creek "has a genuine relationship between two fallible human beings [Maddy, Quentin's character, an investigative journalist, and Jonathan, a magician's assistant, played by Alan Davies]. They are not glossy, they have incredible weaknesses. They are bad-tempered and vile to each other, but that makes them real."

Men Behaving Badly, Quentin reckons, is similarly authentic. "As opposed to being a pretence, it is an honest look at how things work. Men and women do abuse each other, but they need each other, too. That's what people like about it, apart from all the bum and fart jokes."

She dismisses suggestions that the sitcom merely glorifies lagered-up lads. "I'm always pleased when women come up to me in shops and offices and say `Good on you, well done for dealing with the boys'. At first, I thought that it was misogynistic, that it represented boys on top. But now I know it isn't like that. The women are stronger, and they often triumph. They're not the children in the series."

What with her much-publicised split from Paul Merton and her loss of a reported pounds 500,000 when her former agent went out of business, Quentin concedes that "it has been a shitty couple of years, emotionally and financially. But now I feel I'm coming out of it. Work has helped me do that. In the environment I work in, I'm surrounded by kind people - which is not bad when you're feeling lower than a snake's belly. Work has been a solace."

To take further control of her life, Quentin has set up a production company with Men Behaving Badly co-star Neil Morrissey, and owns half of a theatrical agency representing 50 clients. "I decided to set up my own business, so I can see the books, apart from anything else. Talk about getting stung. You live and learn, and I thought this was the best way to make a silk purse out of a sow's ear."

Admitting to being driven, Quentin reveals that she can count on the fingers of one hand the days off she will have in the remainder of this year. "I could sit on a beach for two weeks, but I'm not that interested."

Instead, she is appearing in the National Theatre production of The London Cuckolds until August. Then she is filming Christmas specials of both Jonathan Creek and Men Behaving Badly, as well as directing a production of Terry Johnson's Dead Funny. "Directing is scary. I've frightened myself with the very idea. I don't know why I'm doing it. But I'm under contract, so now I'm obliged to turn up. I must get a hobby."

`Kiss Me Kate' starts on Mon at 8.30pm on BBC1.

`The London Cuckolds' is at the National Theatre, SE1, until August