Documentary-maker Lynn Alleway is a professional provocator. Her two most recent films, Quality Time, a wasp-on-the-wall view of working mothers' relationships with their nannies, and Testing Times, about ferociously competitive nursery schools, whipped up storms of El Nino proportions.

Quality Time, in particular, proved a red rag for working mothers. "People felt that women had worked for years to get the freedom to be working mothers and that I had now made a film suggesting it was wrong," recalls Alleway, herself a working mother. "But all I was doing was trying to show that it's not simple and that you and the kids can suffer. There was a tremendous backlash from a lot of pious working mothers at the NCT [National Childbirth Trust]. I've since been drummed out of the Clapham Working Mothers' Branch of the NCT."

It will be highly surprising if Alleway's latest documentary for the Modern Times strand, Family Values, about different ways of bringing up baby, does not precipitate a similar controversy. As grimly compelling as her previous films, this one compares and contrasts two middle-class families struggling to rear children.

Yvonne from Cornwall, a traditionalist supporter of the Conservative Campaign for the Family, admits that despite her belief in robust discipline her three have "turned into the children from hell". She thinks she and her husband are "terrible parents". As she fights with her 11-year-old son over whether he should be allowed to drive the car, Yvonne snaps: "there may be a law against killing children, but I'm not sure I really care any more."

She goes on to reflect that you "simply cannot get children to do what you want them to do unless you frighten them, and the only way you can frighten a child in my experience is by hitting it. A few more smacks around the place and we wouldn't have so much violence." After lashing out at her son in the car, Yvonne complains that she has broken her nail. Later, she laments that she hasn't brought along a stick to control him.

Amalia from Belgravia, meanwhile, reckons that the answers to the problems of parenting are provided by the New Learning Centre, an institution in West Hampstead that offers both parents and children lessons and counselling. The Centre has 54 rules, including "Don't say `I don't know'," "Don't ask silly questions," and "Control your inappropriate impulses." When Rosanna, Amalia's daughter, is asked which rules she doesn't agree with, she replies: "most of them."

The whole film is enough to make every parent want to send their children back and ask for a refund, but Alleway denies that it is a a stitch-up. "The thing people don't realise is that contributors have their own personal reasons for taking part in my films," she argues. "They tend to be centred around the fact that they feel it's a way of communicating a cause, or they may think the spin-offs will be good for their business. They all have motivations, and they all do it because they want to."

Alleway always makes an effort to give her victims - sorry, contributors - a preview screening of the finished film before it's broadcast. "I showed all the women in Quality Time the film before it went out, and they were fine about it," she contends. "I asked the mother who was in PR whether it was fair, and she said, `You've really captured me there, Lynn.' Another woman started crying after 10 minutes. She thought the film was like a mirror. `I was so awful,' she said. Now she's changed and spends more time with her kids. What upset the women was the unprecedented amount of publicity about the film."

Like Quality Time and Testing Times, Family Values taps into the zeitgeist. Alleway has struck a topical nerve with her dissection of the difficulties of parenting. "From the film, people will see that we've all got something to learn," Alleway observes. "Parenting courses are part of a New Age movement. There's a huge vogue in them; we're all focusing on improving ourselves. People increasingly feel insecure about their own abilities as parents. If you can go on a course where someone tells you you're doing it right, it makes you feel better.

"There's also a very basic instinct to want to do something better than the way it was done to you," she continues. "A whole generation of parents had no philosophy other than barking at their children `I know better than you'. A lot of people have rebelled against that."

So what does Family Values teach us about parenting? That the challenges of child-rearing are universal. "People will see a bit of themselves in the film," Alleway maintains. "Everyone has rowed with their kids in the car. I hope people will connect with that."

Having focused so much on parenting in her work, Alleway draws but one conclusion: "I now want to be at home more with my child and not out and about making these bloody films."

`Family Values' opens a new series of Modern Times on Wed on BBC2 at 9pm