As the addict said to the bishop ...

Tonight at a banquet Cardinal Hume will be handing out drinks. And Tony Blair will sit down to dinner with homeless people and drug users. Paul Vallely explains

Here are four things you need to know about heroin addicts: they are violent, they are dirty, they lie all the time and you can catch Aids from them. That, without resorting too much to caricature, is what most of us believe. As working assumptions, according to Rosalie Chamberlin, who deals with as many 300 hard-drug users at the Kaleidoscope project in Kingston-upon-Thames every day, they are pretty wide of the mark. She will explain why in a moment.

While we are on things that are not quite what they appear, take a two- hour Tube ride across greater London to the Bromley-by-Bow Centre in the East End. Walk into the room at the cornerstone of the place and what do you see?

There are children reading or playing in small groups in each corner and painting messily in the area by the sink. On the walls there are oil paintings and sculptures of rounded nudes. At the centre, separated from the paint and modelling clay by a couple of rows of pine pews, stands a small wooden table, on which a candle flickers beside a vase of flowers. Above it hangs a canopy of cross-rigged canvas that can be raised to the ceiling when the theatre groups or the dance bands arrive. Is it a creche, an art gallery, a church, a theatre, or a dance hall? It is all these, and more.

Appearances are sometimes more than deceptive. They can also be a challenge.

Take the big do in Whitehall's prestigious Banqueting House tonight: among the waiters handing out the drinks when the guests arrive will be George Hume, better known as Basil, OSB, Archbishop of Westminster and a cardinal of the Church of Rome.

A stunt? Well, yes and no. Service, you may dimly recall, is supposed to be the chief ministry of the leaders of a church whose founder was a washer of feet. When the guests sit down to dinner one of the homeless women who have been invited will find themselves sitting next to Tony Blair and one of the drug addicts not far from the Health Minister, Gerry Malone. John Birt of the BBC and the Rev Jesse Jackson, one-time US presidential candidate, will mingle with the dispossessed. Across the capital this weekend there will be 200 other banquets bringing together 30,000 such incongruous guests.

So what is the common ground here? Let me introduce the Social Entrepreneur.

"I first became aware of this breed seven or eight years ago," says Stephen O'Brien, chief executive of London First, a private sector-led partnership that attempts to draw businessmen into decisions affecting the long-term future of the capital. "They are community entrepreneurs who have to make bricks without straw. Somehow they cobble together resources, leadership, goodwill and volunteers, and turn them into a programme to improve the place in which they live."

And not just in London. "Over the past couple of years it's really started to take off," says Alison Coburn of Common Purpose, an organisation set up to break down barriers between the public, private and voluntary sectors. "What they share is a reduced desire to make things happen through national or regional structures. There are some real stars emerging now - creating new things and pulling local authorities and central government with them. The traditional image of the knit-your-own-muesli community organisation is gone. These people are hard-headed, determined and intelligent."

Adele Blakebrough, the director of the Kaleidoscope project in Kingston, is a Baptist minister; she has also become a financier, a fund-raiser, the administrator of a night-club, an expert in methadone therapy for heroin addicts, the overseer of a hostel for mentally and socially unstable young people, and the manager of a staff of 35 doctors, nurses, social workers and support staff. She is also one of the organisers of tonight's banquet. One of the others, Andrew Mawson, runs at the Bromley-by-Bow Centre - as well as the creche, art gallery, etc - workshops for stone- carving, stained glass, portrait painting and sculpture, along with a dance school, a restaurant, groups for the local Bengali women and mutual help groups for the physically and mentally handicapped. He is now busy adding a pounds 1m health centre and an ambitious redevelopment by local people of the neighbourhood's park.

Mawson is also, as it happens, a vicar, but many social entrepreneurs are of an avowedly secular background. What they all have in common is the conscience of the social activist harnessed to the can-do skills of the modern business shaker.

They are children of the Welfare State, adolescents of the Sixties and graduates of the harsh realities of the Thatcherite Eighties, who, having become jacks-of-all-trades, have proved master of most of them and are now determined to wrench the next decade to their agenda.

Not that they would put it like that. "They are the kind of people who in the past would have gone off and founded a national organisation like Shelter," says Stephen O'Brien, "but today they are acting on a much more narrowly focused geographical canvas. They have the kind of skills you'd find in a very entrepreneurial business person, but instead of exercising them to make their fortune, they have decided to use them to improve their community."

This organic growth has been the key. The charismatic Rev Mawson arrived at the URC church in Bromley-by-Bow in 1983 to find a congregation of 10, almost all in their eighties, and a building with its windows boarded up. "It was around the time when Mrs Thatcher was saying there was no such thing as society," he recalls. "We didn't believe that but the congregation did know that what community might mean in the Eighties was certainly not what it meant in the Thirties. We had to explore new ways."

The turning point came when a local woman, a non-churchgoer, asked Rev Mawson for permission to build a boat in the derelict church hall. "It was the only space big enough locally. We met to consider it and one of the elderly ladies in the congregation said: 'Well, Noah built a boat, so why shouldn't Sue?'" Soon afterwards the congregation voted to give not just the hall but all their buildings, church included, to the local community.

The beginnings at Kingston were equally arbitrary. "My father arrived as minister in 1968," recalls Adele Blakebrough. "The church was a great barn of a place that seated 800 and had a congregation of 25 who weren't doing anything much except feel sorry for themselves." Rev Eric Blakebrough insisted that the congregation turn outwards.

At the end of the Sixties, Kingston was an outpost of the capital's youth culture but it was riven by splits between Hell's Angels, proto-skinheads and hippies. Social life revolved around the pubs. "Each group had its own pub. At 11am on a Friday night they would all pour out on to the streets, hang around the railway station - which was all that was open - and fight. We decided to open part of the church as an all-night club for the disaffected youth.

"It was open from 10pm to 6am. To attract them in, we served excellent food [vegetarian] and drink [non-alcoholic]," recalls Adele Blakebrough, who was nine at the outset. "Cappuccino and orange presse were really wow! in 1968."

It worked. As the Kingston Baptists got to know their clientele, it became evident that hard drugs were becoming a serious problem. They discovered that what was being provided by the state was inadequate. After a number of approaches, they settled on a methadone substitution programme.

Which brings us back to Rosalie Chamberlin. She has worked at Kaleidoscope for 10 years, beginning as a nurse but now managing the project's team of four doctors, five nurses and two social workers. "The stereotypes of drug users are largely untrue," she says. "Most of the people who come here are not violent. Coming every day brings order into their lives, they meet people, they build relationships.

"Someone here on a placement from another clinic commented that the attitude of the clients here is quite different; and it is because we don't start off with the assumption that they're here to cause trouble, we respect them. They don't lie to us because we don't put them in situations where they feel they have to." Stereotypes about HIV are misleading; of 251 addicts tested, according to the project's latest annual report, 249 were negative.

The results speak for themselves. Kaleidoscope is the largest drug-dispensing programme in the country outside a major hospital, attracting clients who reject hospital treatment. It pioneered the first British needle exchange scheme and is now running, with Department of Health finance, a pilot "structured methadone maintenance programme" to discover whether drug users will benefit from more intensive forms of support. It runs training schemes for teachers, counsellors and the local police (which started out hostile to the project).

For the new social entrepreneurs there is more to all this than a new pragmatism and willingness to exploit the contracts that come from the Thatcherite reforms of local government and the health service. "The left and right polarity of the Seventies and Eighties no longer describes the world," says Andrew Mawson "The Nineties are about praxis. It's time to cash the ideas in. And if the consequences of what I believe are not good for people, then I have to change what I believe."

In the tradition of English social reformers, he is fuelled by a sense of outrage. He is as ready to turn it on the non-Tory local authority - "see that block of flats? They had pounds 3m spent on new central heating and months later the council announced it was to move everyone out because the block was structurally unsafe" - as he is on the Government - "the poverty trap they have created with their new high rents policy is keeping people out of work and on benefits".

It is an approach that finds favour with both Labour and Conservative politicians. "We had Brian Mawhinney round here," says Rev Mawson, "and within days he approved the budget for our new health centre; the civil servants had been dithering over it for months."

"Civil servants find the new social entrepreneurs difficult to deal with because they are not democratically accountable," says Stephen O'Brien. "But they have a very effective form of accountability: local people won't back them unless they can be trusted. Enormous wads of cash have been invested in urban regeneration in the past 15 years. A lot of it seems to flow straight in and straight out. But with these community entrepreneurs you get a totally different impact because that person knows what the targets are and can galvanise the community. If we were wise as a society, we'd treat these people as heroes and back them most substantially."