Three years ago we launched the Welsh Big Issue in Cardiff before an audience interested in seeing homeless people getting a chance to do something for themselves. The first two speakers were Welsh homeless people who had sold the magazine in London. Each told a story of how they had used the Big Issue to get themselves sorted out. How in a destitute state they had come across us and signed up to sell.

Both speakers told moving stories. How simply by selling they came to take control of their lives and became housed. For the first time in a long time they had felt they had a future.

I was the next speaker. As the founder of the Big Issue I was expected to carry on with the positive mood created by the first two speakers. Instead I found myself telling a different kind of story.

A few months before, a Big Issue vendor who had been with us since the early days had died. A man in his early forties, he had been a chronic drinker since his teens. He had been in the Army and ended up on the streets, drifting through Britain and Europe, getting into trouble and always trying to get together the means for the next drink.

Driven by his habit, he wasn't always particularly polite about getting that money. And then in October 1991 he came upon the Big Issue.

For the next two years he sold the magazine. For once he had to stay sober in the day and keep his heavy drinking to night-time. One day, desperately ill, he went to the doctor. And the doctor told him the bad news. If he didn't give up drink he would be dead within six months. In one fell swoop drink that had been his only comfort was out of bounds. He had a choice.

He chose to go on to drugs. At least, he reasoned, he wouldn't be killing his liver. At least he stood a chance of surviving. Unused to the practicalities of drug-taking, he overdosed and died. Alone in an abandoned house he lost the fight.

Why did I tell this story when the positive side of our work had been so eloquently put by the first two speakers? It wasn't for the drama, though it certainly had effect. No, it was because I felt we needed some honesty. We needed not to participate in the glorification of our work, to exaggerate our successes. It was important that the Big Issue did not succumb to the veneer culture. To be successful, we had to be understood.

A homeless charity's annual report sent to me recently was full of encouraging words, peppered with photographs of happy children playing on swings, mothers in new fitted kitchens. The message was positive. No hint of dissonance. It was all sweetness and light.

But the truth is often different. Homeless organisations have to deal with people ravaged by neglect and self-abuse. Daily they have to work with the contradiction that they can often do little for people beyond holding their hands. But to declare this unsavoury truth of working with destitute people would not go down well. The big funders, government, grant-awarding charities, businesses and the public would run a mile.

Therefore homeless and other charities have to tell the world what the world is comfortable with. To tell the truth, to admit that certain projects for socially and physically reclaiming people didn't turn out as planned, would be the death knell of all their work.

So an industry of half truths has grown up. In the words of Alan Clark in the Matrix-Churchill trial one is "economic with the actualite".

The other night I met a bloke in a pub. For three years he had been working in a safe house for the mentally ill. In this ordinary terraced house 10 people were looked after by social support workers. Aside from offering comfort and accommodation, the purpose of the project was to support people to move back into society. I asked how many people had achieved this during his three years. Slightly embarrassed, he admitted that not one had managed that transformation.

The work being carried out was vital. Ten people were being helped. But the nature of their individual problems meant there was little chance of them gaining the independence written into the programme. To admit that, however, would probably have meant funders withdrawing support. With so much emphasis on a spurious measure of success, the good work of these safe houses could not be explained.

To be economic with the truth is to participate in the veneer culture, in order to hide good but, in the end, unpalatable work.

Political manifestos are not dissimilar. Convinced that the electorate needs to be stroked and lied to, politicians avoid the real problems that beset us. Taxes will stay down. Jobs will be created. Our streets will be safe. Everyone will be trained and educated in order to leap on to whatever super-highway comes along. Order and tranquillity will be restored. Britain will get back to work, etc, etc.

The problem is we all know, or should know, that it is unmitigated balderdash; that manifestos hide more than they expose; that to present a manifesto that exposed the enormity of the problems the country faces would be electoral disaster.

So the party manifestos will show their differing views. The opposition parties will paint a picture of failure - brought about by a neglectful and divisive government that has wrong-headedly pursued injurious policies. But we will not find a trenchant account of the depth of the crisis. For to paint a truthfully bleak picture would undermine their central argument that under surer hands all problems can be solved. If they are too negative voters may be driven neurotically into the hands of the party offering a rosier picture.

Opposition manifestos must therefore walk a fine line. Talk up the failure but leave room for hope. And at the same time show that it can be rectified with a minimum of inconvenience and cost to the electorate.

The incumbents' manifesto, on the other hand, must be full of achievement. No pictures of little children playing in swollen puddles from decayed sewers on inner-city wastelands. Heaven forbid! Rather, not unlike a charity's annual report, all will be positive and well.

This week the Big Issue called for a different kind of manifesto. Not the one that politicians present to us but one we present to the aspirant governments. A manifesto that asks the electorate what they want to see in the best of all possible manifestos. By turning the concept of the manifesto on its head, we hope to publish the issues the public would like to see the general election fought over.

Most people I meet are concerned about the deterioration of society as witnessed on the streets. Yet, for all the discussions on zero tolerance, political debate ignores the fact that the streets are a barometer of society; and that the breakdown in our health service, in education funding, and in the jobs market, often becomes most manifest on the street. To handle the problem of the growing unhealthiness of our streets simply by tougher policing is the most superficial approach.

Numerous polls suggest a deep concern among voters for the plight of the homeless. Yet the huge shortage of affordable housing will not feature significantly in the issues that the political parties will fight over. Nor, to be honest, would it solve the problem of those who have already been pushed to the margins of society.

But there are practical demands to be made. An emergency housing programme would certainly have an impact. Restoring benefits to 16- and 17-year- olds living at home would prevent them leaving home too early and ending up on the streets.

Why not address the reason that housing has had such a low priority: there has not been a minister of housing in cabinet since the 1970s? Who in government is going to speak up for an affordable housing programme when representation is through the Secretary of State for Environment, and at best second-hand?

The manifesto that the Big Issue will draw up from the views of the electorate will, I hope, be honest. It will not conceal the fact that hard work and resources are necessary to right the ship. It will not call for heavy policing to hit out at the symptoms of social decay. It will, I hope, promote the kind of measures needed to deal with homelessness, and the myriad social problems to which homelessness is related, at root. I await your thoughts with interest.

The writer is founder and chairman of the 'Big Issue'.