Geoff Lamb had to shout to be heard over the ever-present drone of the police helicopter yesterday afternoon. The 63-year-old former petro-physicist had worked for more than 40 years in the oil industry, but yesterday he was marching next to a banner that read: "It's your great-grandchildren's planet too - stop wrecking it for them."

"I've spent a lifetime on the wrong side of the fence,'' he said. "We need to radically alter the way we live our lives. Our environment is being utterly ruined and yet it's business as usual.''

Flanked by a phalanx of police officers, Geoff's group of Aberdeenshire protesters were on the move. They, like hundreds of others from all over the country, had come to take part in the climax of the Climate Camp, 24 hours of direct action at Heathrow. After a week of occupying a barren stretch of scrubland bordering the northern edge of Britain's busiest airport, a motley collection of environmentalists, veteran campaigners, local residents and part-time activists had gathered to make their point more forcefully than ever before.

Their mission: to highlight the link between global warming and aviation emissions - and to do it with posters, banners and a healthy dose of purposeful rebellion.

As promised, yesterday's protest involved more than just marching and shouting. The organisers of the camp had always said they expected those gathered between the villages of Harlington, Sipson and Harmondsworth to take part in direct action. They are, after all, the three places that would be wiped off the map if Heathrow's owners, BAA, go ahead with plans to build a third runway.

Just talking about climate change, the camp's inhabitants argued, was not going to make people or the Government listen, and if they had to break the law in order to make the world take the issue seriously enough, they would. Simple as that.

The protest plan was straightforward. At midday, a column of marchers made up predominantly of local residents would head through the village of Sipson and symbolically mark out the route that a third runway would take were it one day to carve through their homes.

Those wishing to take part in direct action, meanwhile, were encouraged to walk to the headquarters of BAA, a nondescript block of offices that lies to the north of Heathrow's perimeter fence, and blockade it. The residents' protest would then join them there and stop anyone going in or out of the offices for the next 24 hours. But the police were taking no chances. Waiting for the protesters at BAA were about 1,500 officers.

Phil Sutton, a resident of Harlington for more than 40 years, was one of those on the first march to highlight where the third runway would go. If BAA gets the go-ahead to build that runway, he and his disabled wife will have to move. "A lot of people say we shouldn't complain, that if you don't want to be moved you shouldn't live next to an airport. But not everyone had a choice. I've lived here since 1963 and my wife has lived here all her life," he said.

But would he be willing to break the law to highlight his case? "Why not? We've been taken for a ride long enough. We've protested peacefully for years against the expansion of Heathrow and it's made no difference. We've been forced to resort to direct action. I just hope no one gets hurt.''

For the early part of the afternoon, the atmosphere in the residents' protest was cordial and at times even jovial. Although one 21-year-old man was arrested for an assault on a police officer, according to the Metropolitan Police, the march was markedly non-confrontational. Police said there had been just three arrests in total - one other for carrying Class A drugs and another for going equipped to cause criminal damage.

Protesters laughed and joked with their police escorts even as they were penned in on Sipson Road for more than an hour. Children dressed in carefully constructed, brightly-coloured costumes marched alongside their parents, who walked next to heavily pierced hippies. Sipson had probably never seen such a varied crowd. Even Daniel Hooper, aka the legendary environmental campaigner Swampy, was reported to be in attendance.

But by two o'clock a very different crowd had emerged from the camp's tent. Heading south towards the BAA offices and Heathrow Airport itself a second column of between 200 to 300 activists left the camp and began walking across a field. Here were the protesters that organisers had promised would blockade BAA at all costs and it was not long before the police helicopter returned and circled overhead.

For much of the next two hours, protesters fought pitched battles with riot and mounted police in waist-high brushland as they tried to make their way towards their target. Communicating by text message and radio, the protesters tried to find a way through the police lines. Many were forced back by police batons and at least one woman could be seen nursing a bleeding head wound.

Yvonne Deeney, a 20-year-old protester who claimed she had been beaten by police, said: "We were standing peacefully next to the fence and then suddenly the police came on to the field to push us back. We were trying to talk to them but they were having none of it.''

Police officers on site said they were unable to let anyone leave the field as protesters doing so would be trespassing on private property.

Although the majority of activists were successfully beaten back, small splinter groups were able to make it through the police cordon and by late afternoon there were reports that a sizeable number had made it to the BAA car park.

Organisers of the march claimed the day had been a resounding success, despite critics' assertions that the turnout - thought to be about 1,400 - had proved a disappointment. Gary Dyer, one of the camp's spokesmen, said: "We're a medium-sized industrial economy. We could be a great test case.. Most campaigns are about more. The suffragettes wanted more of a voice, the civil rights movement was asking for more equality. Climate change is a slightly strange cause because we are asking for less and that's a real psychological challenge.''

To the relief of holiday-makers, fears that flights would be delayed proved unfounded. The protest at Heathrow is planned to continue until noon today.

© 2007 Independent News and Media Limited