by David Smith in Burlington, Vermont

When they passed a $5 correspondence course on making ice cream and opened their first shop in a deserted petrol station, Ben and Jerry were seen as hopeless optimists for believing business could have a social conscience beyond the bottom line.

Thirty years later and now multi-millionaires, Ben Cohen and Jerry Greenfield believe the world has caught up. In a rare interview in their home town in Vermont, the pair identified the rise of ethical shopping, environmentalism and social activism as proof the creed of selfish consumerism has had its day.

Next is world peace. They will visit Britain this week to speak at a concert at London's Royal Albert Hall marking 'Peace One Day', a campaign backed by the United Nations to establish an annual day of ceasefire in conflicts around the world.

David Beckham, actor Jude Law and singer Annie Lennox are supporting the project, which is the latest attempt to bring celebrities together for a one-off concert promoting a global cause.

Cohen and Greenfield, both 56, became the poster boys of 'caring capitalism' as their ice cream business supported farmers and donated a percentage of profits to peace campaigns and charities. But in 2000, Ben & Jerry's, by then a public company, was sold to Unilever for $326m against the wishes of both founders.

Today, while maintaining a link with the business, they devote most of their time and money to social and political activities, including a campaign to shift United States government spending towards education and health.

Greenfield said: 'When Ben and I were younger, environmentalists were referred to derisively as tree-huggers, they were felt to be this radical fringe. You can't get any more mainstream now than being environmentally concerned.'

Cohen is equally optimistic. 'In terms of this generation coming up, there's a big segment that are less materialistic and don't really buy new clothes,' he said. 'They're always buying old, used clothes. I keep on wanting to get stuff for my daughter, who's 17, and she doesn't want anything.' Cohen believes the so-called YouTube generation asks more questions and is less easily swayed by slick marketing campaigns.

He said: 'There's quantitative data that says the younger generation doesn't buy any of this advertising crap. So now you have mainstream corporations still buying traditional advertising but taking a significant part of their ad budget and using it for so-called buzz marketing, guerrilla marketing, hiring people to go around in bars and talk up whatever the hell they're pushing. The younger generation is a lot more skeptical of the mass media world.' The pair argue there is greater mass involvement in social activism than ever before. Cohen cites a book, Blessed Unrest: How the Largest Movement in the World Came into Being, and Why No One Saw It Coming by Paul Hawken, which argues the thousands of small organizations that have sprung up to protect the environment and social justice form the biggest movement the world has seen.

Greenfield said: 'The internet essentially changed everything. There's so much grassroots activity. It's the kind of thing you don't read in newspapers, the kind of thing you don't see on TV. It's these alternative communications vehicles that allow people to work together.'

'Peace One Day', they hope, will be a prime example. It started in 1999 as the idea of one man, British film-maker Jeremy Gilley, who succeeded in persuading the UN to establish an annual International Day of Peace on 21 September. Last year on that date there were initiatives by humanitarian organizations in southern Sudan and the Democratic Republic of Congo, immunization campaigns in nine countries and peace marches, festivals and other events in Britain.

Asked if there was a danger of fatigue with celebrity-led special 'days', Cohen said: 'Everybody wishes there was something they could do besides attend a concert, but that's the best we've got right now. The reality of the society is that the culture is celebrity driven. If there are celebrities involved then the media gets involved and when something's big in the media, politicians have to respond somehow. As citizens, we're doing the best we can. We wish we could do more.'
© Guardian News and Media Limited 2007