''In several airports I've been called out on the carpet,'' she says. ''They look at me and say 'Ma'am, do you have portable electronic devices in your luggage?' and I look at them in a resigned kind of way and say, 'Yes they're vibrators. I make films.' Then they give me another look and I say, 'No, not those kind of films.' You see, I've given a few away at screenings and after a while I wondered why am I - the woman who's made a romantic comedy about the invention of the vibrator and someone who's been talking about them for so long - in any way apologetic about talking about vibrators. So now when I get the look in the airport, I just smile and say, 'Yes it's a vibrator.' ''

Wexler sparkles with enthusiasm and warmth as she speaks. Growing up in Chicago with half sister Darryl Hannah, her family clearly had the movie business in its blood. '' I grew up as a child actor,'' Wexler says. ''Just local stuff on the Chicago stage, but we kind of have a filmy family - my uncle, Haskell Wexler, is a well-known director of photography [he shot, among other things, One Flew Over the Cuckoo's Nest and Days of Heaven], and I have a cousin who makes documentaries. It's either movies or we become shrinks.''

Which is what Wexler intended to do. She studied psychology, but wrote a screenplay during her final year. When she graduated, she showed the script to a friend in the business. ''I made the mistake of putting all the camera movements in the script and my friend said I'd have to take them out because that was the director's decision, not the writer's. So I rolled up the script and enrolled in a masters degree in film at Columbia and became a director. And during that time I realised I was going to be a director director rather than a writer-director. So I had to start looking for other people's material.''

After two feature films and a ''mum gap'' on her CV, Wexler was ready to make a new film and started looking for inspiration. ''Wonderfully, my producer approached me and said, 'Your next film will about the invention of the vibrator in England.' I laughed, but very quickly it became my baby - the one I absolutely had to make.''

Starring Hugh Dancy, Maggie Gyllenhaal and Rupert Everett, the story follows young and handsome Dr Mortimer Granville, who joins a medical practice dealing with women who have ''hysteria'' - a popular diagnosis applied to a range of symptoms, including insomnia, depression and general restlessness. Victorian and Edwardian doctors treated the symptoms with genital manipulation (under a curtain) inducing orgasm. In the movie, Dr Granville (Dancy) finds it difficult to maintain the demands of the job and starts to develop repetitive strain injury in his hands. Fortunately, his friend and patron, Lord Edmund St. John-Smythe (Rupert Everett), is a wealthy enthusiast of new technology and an amateur inventor. When he creates a hand-held electric feather duster, Granville realises that it can be modified to make his work easier. The rest - as they say - is history.

Wexler tells her story with warm charm and wonderful good taste. ''What I love about it,'' she says, ''is that it's not just a romantic comedy but it has a bit more to say. Yes, it's mum's night out but you want to have a glass of wine afterwards and chat about it.'' Wexler pauses and laughs again. ''Of course, we are not trying to solve all the issues of gender and equality through the ages, but there's some important historical information presented in a very funny way. I didn't want to turn it into a history lesson.''

We talk about comedy and the tone of the film, which has clearly been carefully managed. ''I knew in my bones what I wanted,'' she says, ''but it was hard to articulate. I imagined a warm screwball comedy but it's actually quite unusual to make a comedy with a period film. When people asked me what it was when I was developing the idea, I said, 'imagine Richard Curtis, Merchant Ivory and Jane Austen have had a movie baby! This is it.' ''

Wexler is also very clear about where the humour had to come from. ''I knew that the joke wasn't the obvious 'haha, vibrator' thing. We weren't making 'Carry On Up the Vibrator'. The joke is actually the denial - the fact that this was really going on in history and that no one believed it had anything to do with sexuality. So I told the actors to play it straight and let the the humour come from that weird quirk of history. I also made sure that the story kept clipping along.''

And clip along the story does, especially thanks to the character of Charlotte (Gyllenhaal), the independent and emotional older daughter of Granville's business partner, Dr Dalrymple. Charlotte is also a love interest in the story, competing with her sister Emily (Felicity Jones) for the affection of Dr Granville. ''What I love about Maggie's character,'' Wexler says, ''is that she's the truth teller of the story. When she read the script, Maggie said Charlotte was the beating heart of the piece and an unusual character in the era.

''It's she who points out to Dr Granville that he has created an invention that harms no one, gives pleasure to everyone and makes people feel good. Very few doctors in medical history can say that about their contribution.''