You've probably seen, over the last couple of years, one of those investigations into the revolting conditions forced on people who grow the cocoa beans that make our chocolate bars. If, say, you turned on the recent Channel 4 documentary
Slavery, you would have seen a man who had escaped slavery on a cocoa plantation in Ivory Coast giving this message to people in Britain who enjoy chocolate: "You are eating my flesh."

You've probably seen, over the last couple of years, one of those investigations into the revolting conditions forced on people who grow the cocoa beans that make our chocolate bars. If, say, you turned on the recent Channel 4 documentary Slavery, you would have seen a man who had escaped slavery on a cocoa plantation in Ivory Coast giving this message to people in Britain who enjoy chocolate: "You are eating my flesh."

But did that unspeakably piercing moment stop you reaching out, the next day, for your afternoon Twix or KitKat? Or did it just give you a twinge of guilt, quickly drowned out by desire? If the corner shop doesn't stock the ultra-virtuous but more expensive Green & Black's organic chocolate, what's a girl to do when it comes to the late-afternoon blood-sugar drop?

But now, here comes the first super-cheap chocolate bar produced under fair trade conditions. The Dubble bar, launched last week, and soon to be making an appearance in pretty much every supermarket chain and corner shop, isn't a snob product - it is designed to appeal to kids on the bus, snack-hungry people in a hurry, and those who want some change from 50p. Some purists will no doubt throw up their hands in horror - if you want virtuous food, shouldn't you be nibbling organic, locally grown tomatoes? - but there is something refreshingly down-to-earth about bringing fair trade into the mass chocolate market.

It will be fascinating to see how Dubble shapes up. Because it won't just speak of our endless appetite for cocoa solids with crispy bits; it might also tell us something about whether we do, now, feel any power as consumers. Fairtrade, as a specific label as well as an idea, has been around since 1994 in Britain, when it was launched by a series of charities, including Oxfam and Christian Aid, through the Fairtrade Foundation. Although over 50 products sell under the Fairtrade mark in Britain, there is still a pretty low awareness of it - only about 12 per cent of consumers, on the last count, knew about it - and a very low market share.

Why is that? After all, isn't this the generation that is waking up to the reality behind so-called free trade? That demonstrates in front of Nike Town, that marches against the World Trade Organisation, that scorns Monsanto's claims to be a friend of the environment?

This week, the Co-operative Bank will release the results of a huge investigation into ethical consumerism, and whether people's consciences really affect their shopping habits. Unfortunately - but not entirely surprisingly - it found that although 88 per cent of those questioned claimed to be ethical shoppers, only 23 per cent of them could name any behaviour that would justify that claim. Most people said that they just didn't have the information to make judgements on a company's behaviour.

But that response isn't born of laziness. If consumers say they feel powerless or cynical, there are good reasons. For a start, when it comes to ethical consumerism, information all too often turns out to be misinformation. In the Eighties, green consumerism enjoyed a sudden boom, but as more and more companies jumped on the bandwagon, making spurious or exaggerated claims to green behaviour, consumers started jumping off, seeing that they were being taken for a ride. Now that voices are being raised against the iniquities of global capitalism, multinational companies are shouting out their claims to be "ethical", claims which too often evaporate under the spotlight.

Last night saw the screening of a Panorama documentary on the Cambodian factories that produce clothes for Nike and Gap. It was just the latest of many recent investigations that have given the lie to the idealistic codes of conduct that such companies tout through their public relations departments. Those companies know what consumers want to hear - that the workers who stitch the T-shirts are treated fairly, that they have a day off every week, that they are all adults. So they put out reassuring statements saying just that. But it takes just one journalist making one trip to one factory in Phnom Penh to find a sobbing 12-year-old girl and women who work from 6am to 10pm, seven days a week, to get the Gap labels into the sweatshirts.

No wonder we feel confused when confronted with any claims companies make to ethical behaviour. In fact, although we are always being told that the consumer is king, most of us feel utterly powerless when we go shopping. What's more, when we do hear about schemes to develop fair trade with the poorest people on earth, they sometimes seem to smack of an almost laughably naive idealism.

No wonder, then, that the only kind of "ethical" consumerism that has really taken off is not about benefiting them, the distant producers, but about benefiting us, the lucky consumers. Organic food has boomed partly because the benefits to the people we actually know and love - ourselves - are so clear: we buy the goods, we get clean food without pesticides or BSE. Sure, buying organic might also have a knock-on effect on the environment - but that's just an added touch.

And there is a real problem with seeing consumer choices as political acts. All too often, the whole idea stinks of middle-class smugness. It may be easy enough for a select few to drop into some smart food store and pay a premium for organic Fairtrade honey or some gnarled, expensive vegetables from a local co-operative - and then feel good about themselves - but most people in Britain are in a rush and on a tight budget.

But is cynicism and powerlessness the only possible response to the situation we find ourselves in, trundling our trolleys around the superstores? The fair-trade market may still be tiny, but the fair-trade products that have gone mainstream do honestly allow consumers a moment of positive action. They do give people the sense, not entirely undeserved, that by chucking a bit of Café Direct coffee or Dubble chocolate into their supermarket baskets, they might have a tiny, tiny fraction of leverage in an out-of-control world. Because, by making the links from the consumer to the producer utterly transparent, fairly traded products do at least cut through the web of secrecy that makes us feel so powerless.

At the moment, fair trade still operates on a tiny scale. Albert Tucker, who heads up the company TWIN, which supports the Ghanian farmers' co-operative Kuapa Kokoo, which produces the cocoa beans for the Dubble chocolate bar, points out that even that co-operative only makes about 5 per cent of their sales on a fair- trade basis. But that, he believes, has already made some difference to individual farmers' lives.

"It's not charity," he insists. "They are running a proper business, but if they get the guaranteed prices we pay, then they can invest in education, equipment, waterholes for clean water, things like that. It's only gearing up now, but if consumers buy in to fair trade the way they have done with organic, then anything could happen. I can't make huge claims for fair trade yet - nobody can - but we wouldn't be doing it if we didn't think it had a real future. It's about empowering producers, but it starts with consumers. We want consumers to say: we don't want people destroyed so we can eat our chocolate."

n.walter@btinternet.com