From Seattle to guerrilla gardeners on May Day, the activists are learning to do joined-up protest

Rumours are beginning to circulate about what might happen in London this May Day bank holiday. Anarchists are apparently planning to do really scary things, such as tipping manure in front of Buckingham Palace and giving away vegeburgers in front of McDonalds in the Strand, not to mention secret but much-talked about stunts against Benetton and the Millennium Dome.

The police are taking it all very seriously. They have cancelled all leave and planned one of the biggest operations for 30 years to deal with the possibility of the sort of clashes that happened last June in the City of London when they made over 100 arrests.

In a smoky pub in Euston earlier this week, the people who have been fingered by The Sun and the Mail as those "anarchist hooligans" and "yelling louts" who helped to turn the City of London into a "terrifying battlefield" last June, are quietly working on the details of their planned action on May Day. The group is Reclaim the Streets, the action is called Guerrilla Gardening, and it involves protesters turning up "armed', as the leaflet one of them gives me puts it, "with trowels, seeds and imagination" to make little gardens on the streets in central London.

About forty people have turned up tonight. Although the group won't let me sit through the meeting itself, because of the alarmist coverage they receive, afterwards they sit around drinking pints and talking, talking, talking, about what this May Day action means to them. They are a disparate bunch of people whose ages range from late teens to early fifties. One works for London Underground, another is an artist, another is a bicycle courier, another is a teacher. One person I talk to has a degree in political science, one is taking a degree in philosophy, another says he is self- educated.

There is a simmering excitement in the room about May Day's events. "I think Monday will be a glorious day," says one young man with a sleek dark ponytail and a gold ring in his nose. "We're going to take affirmative action to make our environment a better place."

This has to be the most optimistic set of activists the world has seen for a long time. "This isn't a wave of protest," says one German woman with waves of blond hair and wide blue eyes. "This is an ocean. It's like what was happening in '68, when everyone, workers, housewives, began coming out on to the streets. But this time it won't go away."

There is the odd grumpy character in the pub tonight, like the miserable young man sitting opposite me, downing his pints of Guinness, who is as obsessed with media misrepresentation as Alastair Campbell or Posh Spice. But generally, one great thing about this group is their fizzing, hopeful spirit. Reclaim the Streets first came to people's attention about five years ago as the group that took over streets - in Islington, Tottenham and Brixton in London, as well as cities all over Britain - illegally and merrily, to hold huge, day-long parties. If you went to one you were told that it was about reclaiming the streets for the people against the domination of the car, but you could also just go and dance to the sound system in the sunshine.

Gradually, they developed a more fiercely political stance. "We stopped being seen as fluffy greenies," says the pony-tailed man. It was on June 18 last year, with the protests in the City of London, that Reclaim the Streets began to ride the global wave of activism devoted to "anti-capitalism'. Under this umbrella word, anti-capitalism, a lot of different viewpoints can be tolerated - some people in the room tonight would call themselves anarchists, others socialists, others environmentalists, others squirm at the very idea of a label.

"That was the achievement of June 18," says the grumpy young man, who calls himself Darren, "it put this word, anti-capitalist, out there. On the front page of the Financial Times the next day it said, `Anti-capitalists lay siege to the City of London'."

The protests in Britain last year, on 18 June in the City and 30 November at Euston station, involved some ugly scenes in which activists and police clashed, and for some people that will remain the image of the day - the photographs of bleeding protesters and police going in with riot gear. The bitter debates about who started the trouble, the police or the protesters, rumble on, and unsurprisingly, everybody who speaks to me insists that throwing banner poles or broken bottles at the police has nothing to do with their aims. Certainly, Reclaim the Streets hates being represented as a bunch of kids looking for trouble, and when one of their number says to me, "I like to persuade people. I have an iron bar that's very persuasive", everyone bursts in to reassure me that he's joking.

Indeed, the group here tonight gains much of its confidence from the knowledge that beyond this little pub is a general swell of sympathy for this brand of activism. Reclaim the Streets is only one of a series of groups, such as Corporate Watch, Earth First, The Land is Ours, Solidarity Federation, which have been exploring various methods of direct action, alongside larger green groups such as Greenpeace and Friends of the Earth. They can count on a lot of public sympathy as well as attention. The failed trial earlier this week of Lord Melchett and 27 other Greenpeace activists who ripped up a field of genetically modified maize showed that people who act out their dissent from government and corporate policy aren't necessarily going to be condemned by the public for breaking the law.

What's more, this wave - or ocean, if you like - of anti-capitalist activism is not confined to Britain. The way the people with Reclaim the Streets see it, it's a constant volley of inspiration that ricochets around the globe. What's been happening in Britain is particularly helped by transatlantic connections. "At the beginning of the Nineties, people from Earth First in the United States visited Britain," Al Parsons, an articulate man in his thirties who has spent time with the activists in the States, tells me. "That helped to set off a whole wave of environmental protest here - like Twyford Down, the M11. And then our street protests helped to inspire the activists in the USA to develop the protests at Seattle and last weekend in Washington."

Even world leaders now feel compelled to respond to these activists. During the protests in Seattle and in Washington politicians, including Bill Clinton and Gordon Brown, gave interviews to say that they took the concerns of the protesters seriously and were joined with them in wanting to attack global poverty. They did so because they knew that many people would be looking with more sympathy at the kids on the streets than the men in suits in the conference chambers.

That's because much of the rhetoric that comes from these protests is striking a chord with the wider public. The activism of the Eighties and Nineties tended to be devoted to single issues, to animal rights, say, or the poll tax, or nuclear weapons, or road-building. But activists today are linking up various single issues into a more general mood of dissent that touches all kinds of people. Individuals of all ages and backgrounds are disillusioned with mainstream politics and its apparent inability to turn back the tide of environmental destruction and the widening gap between rich and poor. But is this activism really presenting any alternative, or is it just a picturesque let-out for people's frustrations?

"More and more people want to get out there and do something," says Tony Wood, who has participated in anti- nuclear and anarchist activism for over 20 years. "But a lot of them just go along to a protest and think, `I've done my bit'. We're going to need a lot of organising if we're actually going to change anything." To try to develop the issues that lie behind all the disparate groups and ideas that sit under the "anti-capitalist" label, there will be a conference in Holloway, north London, over the weekend before the May Day bank holiday, with workshops on revolutionary history, alternative education, and workplace organising, by speakers from all over the world. "It will bring activists together, and, hopefully, bring in people from the local communities to have their say," Mr Wood says.

It's impossible to know ahead of time how many people will turn out on May Day and how many of them will want to make little gardens in Parliament Square, how many of them will want a scuffle with the police, how many will want to sit and discuss workplace organising, or how many will just want to walk in the sunshine and meet friends. The police don't know how many will be out there, and who will be doing what, and neither does any one group of activists, since there are so many different groups involved, and every one of them relies on an unpredictable grapevine.

But if May Day goes according to some of the activists' brightest hopes, it may move the debate on a bit. Al Parsons is one of the most enthusiastic of this enthusiastic group.

"The Guerrilla Gardening action is important," he tells me, "because it shows we're not just against things. It's not focused on the WTO or the IMF or whatever. People often say, `OK, we know what you don't want, but what do you want?' We want to start to create an alternative. The gardening action is about everyone participating. It's an experiment in taking back urban land and using it freely - as a meeting space, as a provider of food."

And does he really think that this kind of event could make the big businesses and vested political interests that rule the world think again? "Well, look," he says, "revolutions can't be predicted. But they need hope and a sense of possibility. Reclaim the Streets has that hope. I think this is just the beginning."