Hester Lacey on the portraits that are shocking South Kensington
EVA HERZIGOVA stopped traffic in the Wonderbra ads by just standing there in her underwear; now another model of a quite different vintage is having the same effect. Melanie Manchot's photographs of her 66-year- old mother in vest and knickers have been blown up to billboard size and are currently on show in Pelham Street, South Kensington. Melanie, who trained at the Royal College of Art, has been working on nude studies of her mother for the past three years (she wanted to use some of her nude portraits, previously featured in Real Life, on the billboards, but the poster site company balked at the notion). Gallery exhibitions of her photographs have been well received; but, she explains, "I always wanted to do something more public - take the work to a broader audience."

Melanie's powerful portraits challenge conventional ideas of desirability, beauty and age. This particular exhibition, devised in partnership with curator Mark Segal and funded with the help of a grant from the National Lottery's "Art for Everyone" initiative, cocks a snook at bra-selling supermodels. "It is a contrast to all those lingerie advertisements," says Melanie. "A lot of these ads are supposedly trying to show women in an empowering way, but they perpetuate the image of all women as young, slim, fit - they fall back on the beauty myth even if the copylines are saying 'I'm doing this because I want to and to please myself'. These billboards are a counterpoint to that supposed ideal."

It's a big step from gallery space to billboard space. "I realise that some reactions could be negative, but I believe in my work and want to take it to more people - taking the risk is positive," says Melanie.

So how have the genteel streets of South Kensington welcomed Mrs Manchot, their newest visitor? The posters themselves are highly striking; the row of five each shows a larger-than-life figure, standing confidently alongside slogans such as "No longer object but subject". Last week passers- by were stopping to have a good look. "I think it's wonderful," said Susan Wallace, herself in her sixties. "It's great to see an older lady who is still proud of her body. I only wish I looked as good. I think she is to be congratulated on her bravery."

Three twentysomething women were convulsed with giggles. "I suppose we're all going to go that way one day," said Suzanne Dax, 23. "In a way it's scary, that your body will change and there's nothing you can do.""It's excellent," commented Lisa Graham, 34. "I am sick to death of being constantly confronted with young, slender babes with enormous tits. I think these should be left up all year to remind the people in the clothes shops over there that there is more than one body shape in the world."

Men were less enthusiastic. "I can't see the point of it. It is just meant to shock," said a passing businessman. "Urgh," added one young man succinctly. "I don't like it," he elaborated articulately, when pressed for a further opinion. "This independence is intimidating," reads one of the poster's slogans. It certainly looks like it.

Melanie Manchot's work is on display in Pelham Street, London SW7, until January 15, and there is a complementary exhibition at The Blue Gallery, 93 Walton Street, London SW3, open 10am-6.30pm