Ever since Cathy Come Home, he has been both one of our most critically acclaimed and most politically aware film directors, and now he's drumming up support for the Respect party. Nick Morrison catches up with Ken Loach on the campaign trail.

For someone who has spent the last four decades raging at the system, Ken Loach is very softly spoken. So softly, that sitting in the caf at Darlington station, with constant announcements and trains arriving and departing, it's a strain to make out what he's saying.

But perhaps it shouldn't be a surprise, for his is a reserved sort of anger. Not for him the spectacular pyrotechnics of Michael Moore; rather, his way is a slow-burning hatred of injustice, and a quiet hope that while the situation looks bleak now, there is a better world up ahead.

From Cathy Come Home and Kes in the Sixties, via Riff-Raff, Ladybird, Ladybird, Land and Freedom and Carla's Song to My Name is Joe, Sweet Sixteen and his latest release, Ae Fond Kiss, Loach's films have documented the struggles of ordinary people, against homelessness, poverty, drugs, but mostly against authority.

He's just stepped off the train on the way to lending his support to John Bloom, candidate for the anti-war Respect party in tomorrow's Hartlepool by-election. In between a tour in the Respect battle bus and a rally with George Galloway MP, there is a masterclass with students from the town's sixth form college.

The son of an electrician from Nuneaton, Loach has been a lifelong socialist, but it was the Iraq war which galvanised him into political activism away from his films.

"It was the knowledge that it was plainly an illegal war and it was based on lies and the most outrageous political deception I can remember," he says, over a frugal glass of tap water.

"I think that was a very common reaction and events have borne that out: it has brought chaos and mayhem to that part of the world, because of corporate interests."

How does he view Tony Blair's contention that, even without Saddam's weapons of mass destruction, the world is a safer place without the Iraqi dictator in power?

"I don't think it is a safer place because they have embarked on this project that is unlimited warfare. They say it is a war on terror, but terrorists are who they decide they are.

"And even on Saddam, the corollary is that you have international lawlessness where vigilantes go about taking out who they wish, and they have perpetuated so many corrupt dictatorships it plainly was not about that."

He may be softly spoken, but there is a fierce conviction in his voice, and a simmering anger at the devastation wrought by British and American policy.

"In ten years of British and American-led sanctions, the country was crippled and the UN man on the spot said half a million children died," he says, shaking his head in horror.

'And since the war began we don't know how many have died because they refuse to count them. We would all be better off without dictators, we would all be better off without George Bush, but we're not going to hire a hitman."

Now 64, he was a member of the Labour Party for 30 years, sticking with it even when the leadership lurched to the right, because there were still people who believed in the same things he did.

"That is not the case now," he says. "New Labour has reshaped the party in its own image and there is no left, or virtually no left. Even when they say they want to renationalise the railways, the leadership takes no notice."

It's fair to say he's not one of those arts figures who've become disillusioned with Tony Blair, because he was never illusioned with him in the first place, but it wasn't a disagreement over policy which eventually saw his membership lapse: it was when the party didn't want to come calling for his membership fee, they wanted it by direct debit.

"There were a number of issues, the whole leadership of the party, its social policy, its failure to support the miners, but I hung in there until they said we're not coming to see you, just give us your Visa number.

"I thought they don't really want members, they want subscribers, so I just thought f**k you," he says, half-suppressing a laugh at his characteristic hankering after the personal touch and reaction against authority.

It was frustration that there was no political party representing the views of the million or so people who took to the streets to demonstrate against the war that led him to back Respect, but he insists he does not despair at the lack of mainstream support. Instead, he takes comfort in the hope that the groundswell of opinion will eventually prove irresistible.

"There is a huge swathe of people who share the same concerns. Apart from the millions on the war march, there is the whole of the globalisation movement. It just isn't formulated into a political programme.

"People will always fight back. Maybe they go through periods where they seem very quiet, but eventually they will fight back, that is one of the lessons of history.

"In the short-term, the particular choices are not encouraging, but in the long-term I think there are grounds for optimism. Otherwise you would put the gas on. If you look for green shoots they are there, even though the winter's long," he says.

He sees Respect as uniting opposition to the war with opposition to privatisation, in the belief both causes have a single enemy: big business.

"The drive to war was led by big American corporations, the same as the drive to privatisation, which again is in the interests of the big corporations.

"You look at who is taking our health care provision and who is running the war; it is the same motive that is putting us both into war and destroying every concept of public service," he says.

He is scathing about Tony Blair's government: its single achievement is the establishment of Supporters Direct, a way of enabling football supporters to form trusts with a view to getting a seat on the board - again his championing of the ordinary person comes through. "I can't think of anything else they have done," he says breezily.

His latest picture, Ae Fond Kiss, was released earlier this month, and he's just finished working on a film in Italy, where he directed one of three stories set on a train. "I'm scratching around with the writer I work with, Paul Lavery, to do another film, but I don't know what it is yet," he says, before correcting himself: "I do know, but I daren't say it."

His films have generally been more successful in the rest of Europe than his homeland, with Ae Fond Kiss looking like making five times as much in France as in Britain. "They have a huge tradition of serious film-making, which we don't have," he says, but he insists he wouldn't trade his beliefs for greater commercial success.

"Just occasionally you get a bit fed up with it, a bit p****d off from time to time, but you just have to see it as the bigger picture. All you can do is be true to what needs to be done."

Before he's whisked off to Hartlepool, he steps out of the caf and back onto the platform for a photograph. It's clearly the least enjoyable part of his day.

"I hate being photographed. I could talk all day but I hate photographs. They say 'Smile' and I think I am smiling. Obviously I'm stuck in a frozen rictus of anguish," he muses. Perhaps that's what 40 years of rage does for you.