As hundreds of thousands of Britons flock to the capital today to protest against war in Iraq, Paul Wllis reports from the front line at a peace demonstration he attended earlier this week.

OUTSIDE the nondescript north London tube stop, a small but vocal crowd is gathering. Clustered together in the blustery damp of a January morning we are here to protest against the war in Iraq.

One of the organisers moves through the crowd handing out cards to the demonstrators. A group of about half a dozen middle-aged women have formed themselves in to a kind of impromptu choir in the middle of the throng and are singing out in defence of peace. On the other side of the road, a robust and intimidating line of riot police stares across at us.

I read the card that has just been handed to me. On the front is the number of a London solicitor. On the reverse is printed: "If you are arrested, stay calm" and a brief resume explaining your rights. Just then a police officer appears beside me. "What's that then?" he asks me, nodding at the card.

"It tells me what to do if you lot nick me?"

He shakes his head gravely: "I don't know," he says, "you conspiracy theorists."

The purpose of today's event is a blockade at the entrance to the British Military Joint Forces Headquarters at Northwood. Any British-led contribution to a war on Iraq would be directed from this base, discreetly situated in the leafy suburbs of north London. Blockading the entrance to the base is - the police have already assured the organisers of the demo - an arrestable offence.

Among the mixed bag of demonstrators is a fair smattering of ex-hippies and stalwarts of the Campaign for Nuclear Disarmament - long-term activists, you might say.

The policeman's jibe about conspiracy theorists is old news for many of these protestors. During the 'greed is good' heyday of Mrs Thatcher, these liberals were mocked as the 'loony left' - as if fighting for social justice and peace were a symptom of madness. Today, they are "conspiracy theorists" or "anti-capitalists". Some no doubt revel in these titles, but this is only half the story.

Among the marchers here today is Sue, a middle-aged mother of two from Bournemouth. She travelled up yesterday and despite suffering from acute arthritis, she spent last night on the floor of a community centre in east London with fellow protestors. She admits that as a consequence of all the walking and the night on the floor, she will probably spend the next week or so in bed.

"I've never done anything like this before," she says, echoing the sentiments of many I have spoken to. "It's just I felt too strongly about this issue to stay silent."

She is with her daughter Rachel, who she coaxed along to today's event. Rachel, too, is new to demos, but says her mum's example inspired her to make a stand. "The first event mum went to was at the end of last year. It was a 'die-in' - which involves everyone lying in the road pretending to be dead," she says. "She came to my work afterwards with all these tassels in her hair and covered in anti-war badges. I don't know what my boss thought."

Sue shrugs her shoulders and smiles. "It doesn't really matter what other people think, does it? You just do what you believe is right."

After a few more megaphone instructions, the demo starts off. Despite the dismal weather and dull surroundings, it feels like a carnival. A troupe of drummers beat out an infectious Latino rhythm but centre stage is reserved for a psychedelic bicycle contraption called the 'Rinky-Dink'. Peddled by a crusty-looking type with four-day stubble, this eco-friendly techni-coloured dream bike has its own sound-system and microphone, and works entirely on pedal power. It even blows bubbles.

Many of the protestors who have taken to the streets in the last few months to oppose the war have never demonstrated before. Recent events in London and around the country have drawn crowds numbering in their thousands - a rally through the centre of London at the end of September last year was attended by more than 150,000 protestors, according to police estimates (though organisers put the figure at more like 400,000). That rally was marked above all by its diversity - Muslim groups walked alongside pensioners from the Home Counties and university students.

There is a further demonstration taking place in London today and police admit they are expecting more than 400,000 to turn up this time.

But the more direct nature of this event at Northwood, with its added risk of arrest, means the numbers are in the hundreds rather than thousands. It has been organised by a collective of peace campaigners, the main impetus coming from a group called Voices in the Wilderness, which was first founded in America in response to the humanitarian effect of UN sanctions on the Iraqi people.

Looking around at the marchers as we snake our way up to the base, what is most striking is the number of middle-aged women taking part. Many of the organisers are also middle-aged women.

I speak to Charles, a journalist from Manchester who is attending the demo and has recently returned from doing aid work in the Palestinian occupied territories. Out there too, he found that many of the volunteers were from the same group. He talks about 'a journey of empowerment'.

"Many of the women started off protesting in the 1970s and 1980s and have become more and more active ever since," he says.

His experiences convince him that most people don't believe there is a global conspiracy hatched in the West to keep the Third World from developing. "A more widely held view," he says, "is that the Western powers are only concerned with their own interests and protecting their dominant position in the world. And if, as a consequence of that, the world's poorer nations are kept from developing, well that's just tough."

But perhaps the misconceptions are not all on one side. As the demo draws closer to the entrance to the base, we are stopped in our tracks by a row of police vans. While we wait, the drummers continue to play and eventually an announcement is made that the police are going to allow us through to blockade the entrance to the base.

If recent newspaper polls are to be believed, a majority of the British people oppose unilateral action by America and Britain against Iraq. This majority is sure to include more than a few members of Her Majesty's Constabulary. So as a spontaneous chant of "police against the war" breaks out among the demonstrators and the sun makes a belated appearance in the sky above us, I am sure I see one or two quiet smiles from the men and women in blue.

* For more information visit: www.stopwar.org.uk