John Stewart: A one-man eco-industry

Where would you expect to meet a man described by an awe-struck fellow campaigner as "one of the great eco-warriors of our age"? Swinging through the rainforest, maybe? Riding the bows of a boat into battle against whalers? Not eating a sandwich in a very dull hotel on the edge of Heathrow. But there he is, John Stewart, the most influential environmental activist in Britain, revealed today to be top of The Independent on Sunday's Green List. Step aside, Prince Charles. Make way Zac Goldsmith. Bow down Joss Garman, co-founder of the direct action group Plane Stupid, who gave the quote above and says of Stewart: "He is a total hero of mine, an absolute inspiration to the movement as a whole."

What, this 61-year-old, tucking into a panino? This man in a black fleece, who looks like a gloomy heating engineer on his lunch break? Yes. "I'm chuffed," says Stewart quietly. "It's an accolade." It is. So where is the proof that he deserves it? Look first to the streets of London, at those lovely old houses not demolished in the Eighties to make way for huge highways. They stand as the result of a campaign led by John Stewart. Now consider the woods and valleys around Britain not covered by tarmac in the Nineties. Roads were not built through them, as the result of another Stewart campaign. He didn't dig himself into a tunnel like Swampy, or chain himself to the branches – but he was the man the protesters credited with making sure that their passion was understood, and ultimately embraced, by Middle England.

Now Stewart seems on the verge of another victory, this time against expansion at Heathrow – a cause that has occupied almost his every waking hour for the past decade. It has made his social life "a disaster" and kept him poor and single. Heathrow is also what landed him on the front pages and in the High Court two summers ago, when the airports operator BAA tried to ban sympathisers from joining the climate camp on the perimeter. It succeeded only in obtaining an injunction against the three people it felt most threatened by – one of whom was John Stewart.

If you want to know how influential he has become, listen to David Cameron. The Conservative leader recently surprised opponents by declaring his opposition to the building of a third runway at Heathrow, saying: "The economic case is flawed." The evidence he used to back this came from a report published by Stewart. So did the thrust of Cameron's argument, and the key phrase: that business wanted "a better Heathrow, not a bigger one". He even took Stewart's suggested alternative – a high-speed rail network – and made it his own.

"We were quite gratified," says Stewart, who has "never sat down" with the Tory leader but did have lots of chats with senior figures in the party. Not that he wants to be seen as a supporter. He believes Cameron's statement to be "the death knell for the runway" but won't stop campaigning now. He probably couldn't anyway, having got this far without ever having any other kind of full-time job.

How did this life of agitation start? John Stewart's family was not political. They were crofters from the Highlands "who knew their place". He was born in Rhodesia, but raised in Edinburgh. Even after studying social policy at Bristol Polytechnic he moved to London and did ... "not much". But this was Brixton at a time of great turmoil, just after punk and before the riots. Surely it was the Clash who politicised him? Or Mrs Thatcher? "No," he says. "It was the 2B bus."

He laughs. He's not humourless, although very intense. You can tell he's used to cutting through silly pub talk with his arguments. "Ken Livingstone's GLC was elected on the promise of cheap fares. Those were, in very dubious circumstances, ruled illegal. Sheer fury drove me to get involved. That was the start."

Anger drove Stewart to become a campaigner and a transport expert, employed as an adviser to local authorities. He was green when people thought that meant Martian. "Yes, you were bonkers. I did see public transport as a way forward, for environmental and for social reasons."

First, he fought the Conservative plans for the capital, with a campaign called Alarm – or All London Against the Road-building Menace. It was done on a shoestring, but he found the tactic that has been his trademark – getting the most extreme and the most conservative of people to work together for a common cause.

Next, Alarm went national, to oppose 600 new or improved highways. Stewart was as startled as everyone else at the "explosion" of direct action at Twyford Down and beyond. While the television cameras watched diggers trying to oust human moles, he was busy organising, negotiating, mediating and doing everything possible to ally the Dongas and other new protest tribes with more traditional campaigners, lobbyists and politicians. "I don't think they would have succeeded on their own," he says. "They would have been marginalised. We gave them respectability, an access point into politics, and allowed other people to demonstrate their support for direct action that they wouldn't take themselves."

Public opinion shifted. Of the 600 road projects proposed by John Major's government, only 50 survived under Tony Blair. By then aircraft noise had started to become a problem in Brixton, where Stewart lived. People who knew his background asked him to campaign. "I hesitated. The thought of starting all over again... but the aircraft were really starting to bother me."

Taking up a new cause came at a cost: Stewart lives alone, without a partner or children. Joss Garman, whose Plane Stupid activists gave him a standing ovation at a gathering last weekend, says: "He never stops, every day and night, even at weekends." Despite all his networking, Stewart admits, "I am essentially working alone." He can't earn much. "Oh, you've worked that out, have you? The taxman just couldn't get his head round what I was doing. I had to send him press cuttings. There is nothing else, no other source of income. If only!" He has a flat in Leytonstone, east London. "If I did have kids, things may well have been different. You've got responsibilities then. I have had partners, but this lifestyle is not very good for your love life."

Does he regret that? "I sometimes... yeah." Everything you ask John Stewart is answered carefully, in sentences built for radio or television. Talking about himself, though, there's a slight sense of dismay. "In some moments, I think I probably do. I remember going on the train to Brussels, to a meeting of European campaigners around airports. Of course, most people on that train were going on holiday, or for romantic weekends."

There was a lot of hand holding? "Exactly. I thought, 'Wouldn't it be nice to forget the fucking meeting and have a nice weekend in Brussels?'" He sighs. He didn't though. "I enjoy the campaigning. No, I enjoy the successes." Like stopping the roads. Persuading Cameron. "Nobody could go on with this lifestyle if there were no successes. It's an odd sort of life."

For 10 years he has been the chairman and sole employee of the Heathrow Association for the Control of Aircraft Noise (Hacan), which started as a group of concerned people in Kew and now has 6,000 members across London. Stewart has also become the de facto leader of the extraordinary nationwide coalition of dreadlocked radicals, stressed-out residents and concerned councillors who believe that airports are becoming too big, too noisy and too destructive. But his efforts were not national news until the arrival of the solar-powered circus that was the climate camp in the summer of 2007, provoking tabloid hysteria and a massive police response.

Yet the protesters were actually quite non-confrontational. Hacan does not organise direct action. However, Stewart says there is a change of mood. "I think the coalition – or parts of it – has got to become more threatening, so it's not just demonstrations, stunts and flash mobs, although that's terribly important. There are differences in the movement as to whether violence against property is justified. My own view is that in certain circumstances, damage to property can be a legitimate tactic."

Never against people though. "That is one of the definite things." Stewart keeps his voice low as he talks. Outside, jets are thundering through the rain. Inside it is gloomy, but perfect for anonymity and seditious talk. "It will need to be very active, very public." That could mean the disruption of flights, terminals, baggage, transport links or anything else the protesters can mess up without getting shot or arrested as terrorists. Stewart won't be specific. He can't. The aim must be "to put doubt in the minds of business: is it worth doing this?" Who will they try to get at? "Not just at BAA and the Government but at people who may well finance and build a third runway at Heathrow."

The decision last week to allow 70,000 more flights a year at Stansted in Essex means "it is inevitable you will see direct action there by the end of the year", he says. The Government is also expected to approve the building of the third runway at Heathrow in the new year, and protests will likely follow in the spring. Once again, Stewart's almost private obsession will become a national one.

Doesn't he feel just a bit let down by the climate campers? They could have kept up the pressure in the summer, but seemed to bottle out and avoid Heathrow in favour of trying to close a power station instead. "No," he says firmly. "We have not been abandoned. They have identified aviation and coal as two big issues for them, and this year they wanted to concentrate on coal." There he goes again, holding the forces together.

Stewart's battles: From the 2B bus to Heathrow's third runway

Early Eighties Young post-graduate gets worked up about the 2B bus, becoming transport expert and campaigner. Opposes abolition of cheap fares introduced by Ken Livingstone's Greater London Council.

Late Eighties First victory, as Conservatives abandon most plans for road construction across the capital. Fight has been led by Stewart's Alarm, or All London Against the Road-building Menace, co-ordinating 250 campaigns.

Nineties Alarm goes national after Margaret Thatcher's government proposes 600 new or improved roads. Stewart acts as a link between the new-style environmental protesters at Twyford Down and Newbury, and more traditional campaigners. Labour acts on shift in public opinion and drops all but 50 of the projects.

Noughties John Stewart becomes chairman of Heathrow Association for the Control of Aircraft Noise (Hacan). Takes leading role in opposition to airport expansion, again uniting local campaigns and politicians with radical protests such as the 2007 climate camp.

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