Until this week, Mr Pereira's voice was drowned by the roar of jet engines. The people of the villages around the airport have been campaigning for years against the threat of expansion, but no one in power has listened. Both the government and the airports operator BAA appear determined to evict the living and raise the dead.

Heathrow is already the busiest international airport on earth. The new runway and the terminal and approach roads it needs would demolish around 1,200 homes; one primary school will be flattened; six others will be permanently blighted by noise. Separated from the rest of Heathrow, this would, in effect, be a second airport.

The government hopes to have the new airport built "as soon as practicable" on the grounds that it will "generate the largest direct net economic benefits of any new runway". The Times reveals that BAA has been allowed to influence the tests that will determine whether or not the runway would breach the legal limits for pollution and noise. The government has also given the company the results of its air pollution studies, while withholding them from the public.

It seems pretty obvious that this scheme could go ahead only if the government is prepared to rip up both its agreements with the public and the European Union's pollution laws. When Heathrow's fifth terminal was approved, a planning condition capped the number of flights using the airport at 480,000 a year. The new runway would raise them to 720,000. BAA also wants to end the "alternation agreement" that regulates flights at Heathrow's existing runways: planes leaving the airport currently switch directions at 3pm in order to give the people of west London a break from the noise. If the policy changes, the airport could take a further 72,000 flights a year.

The government has promised that the area of land subject to noise levels that the World Health Organisation defines as causing "serious annoyance" (57 decibels or more) will not increase. But its own forecasts suggest the new runway will expand this zone by at least 12%. This is almost certainly an underestimate, which is perhaps why it has refused to publish maps of the flight paths to and from a third runway. A consortium of local authorities has drawn up its own maps. They show a massive northern expansion of the noise zone, sweeping over much of London and the counties to the west of Heathrow.

The airlines say that they will make their planes quieter in order to meet the government's promise. But they also say they will make them more efficient to reduce emissions of carbon dioxide, and the method favoured by some of them is to swap the current engine design for "open rotor" turbines, which are much noisier. They can't have it both ways.

Already the planes and their associated traffic have been breaching the European Union's limits for nitrogen dioxide pollution, which suggests that current airport activities are unlawful (remember that when you hear ministers fulminating about our illegal protest). Now we are expected to believe that air pollutants can be reduced to a level below the legal limits while the number of flights almost doubles. It looks as though our civil servants will be busy with what they call "statistical interpretations of the target". The rest of us call it lying.

Camping in the fields north of the airport over the past week, I found that I fell asleep promptly at 11, when the flights mostly ceased, and woke - despite my wax ear plugs - promptly at six, when they resumed. My throat swelled and my eyes itched, and I am sure that my headache was not just the result of a few too many bottles of Pitfield's Eco Warrior. Even if we were to put climate change to one side, who can honestly claim that new runways, for all their economic benefits, improve the quality of our lives? A pall of skull-scraping misery hangs over the catchment area of every major airport. But the business plan cannot be faulted: the more hellish our lives become, the more we seek to escape from them.

Of course we cannot put climate change to one side. In a previous article I showed that, depending on whether you believe the government's figures or those produced by academic researchers, by 2050 the greenhouse gases produced by the UK's air passengers will equate to between 91% and 258% of the carbon dioxide the government says the whole economy should be producing. Its airport expansion plans, in conjunction with those of other nations, will cause runaway climate change even if we were to spend the rest of our lives shivering in the dark. So much for the economic benefits of new runways.

The people seeking to prevent this expansion know that when the government supports a development, explaining your objections at its public inquiries is about as much use as shaking your fist at the sky. An elaborate theatre of consultation and democracy is designed only to hide the fact that the decision has already been made.

So what else do the critics of direct action expect us to do? How else do they suggest we drag this issue out of the shadows and thrust it to the front of the public mind?

We did not get everything right. The media strategy was hopeless: sympathetic journalists were excluded, while unsympathetic journalists went undercover and stayed in the camp for as long as they wanted. But in other respects it was better organised, more democratic and more disciplined than any I have seen before. It drew on the protests of the 1990s but introduced two new elements: much better logistics and a model of popular democracy imported from Latin America.

All the facilities that 1,500 people would need - including running water, sanitation, hot food twice a day, banks of computers and walkie-talkies, stage lighting, sound systems, even a cinema - were set up in a few hours on unfamiliar ground, in the teeth of police blockades. A system of affinity groups and neighbourhoods, feeding their decisions upwards to general meetings, permitted a genuine participatory democracy of the kind that you will never encounter in British public life. The actions themselves were disciplined and remained non-violent, even when the police got heavy. I left the camp on Sunday evening convinced that a new political movement has been born.

We haven't prevented runaway climate change by camping beside Heathrow and by surrounding the offices of BAA, and nor did we expect to do so. But we have made it harder for Alf Pereira and the other invisible people to be swept aside, and harder for the government to forget that its plan for perpetual growth in corporate utopia is also a plan for the destruction of life on earth.

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