It has been billed as the Party for Peace, and Dan, my 13-year-old son, has looked forward to it for ages. By now a veteran of Stop the War Coalition marches, student meetings, pickets and media interviews - plus two school walk-outs - he has had a rapid politicisation entirely out of my hands. But this event - a gathering at Parliament Square, from 4pm, “for all students who love to party and hate war” - is being billed as a good time. He will be going with his friends, he says, will be back late and is dismayed to learn that I am going too.

Perhaps the timing is the problem. The party is taking place on April 10, the day after Saddam Hussein (in bronze, at least) fell in Baghdad. The statues in Parliament Square are shrouded in green plastic burkhas, their bases boxed in with chipboard, in an attempt to prevent paint-splattering of the kind that befell the monuments to Viscount Palmerston and others on March 20, the day war broke out. It takes some ingenuity even to get into the square, ringed by waist-high metal crush barriers that line both sides of the pavement opposite the Houses of Parliament.

It’s a forlorn affair. While Estelle Morris and Douglas Hurd hurry in the other direction - into the mouth of Westminster underground station - teenage boys are play fighting on the damp grass using the sticks from placards. Police officers - suddenly looking much older - stand by with their arms folded. Labour anti-war rebel George Galloway is expected, says one of the boys, hopefully, and a band called Fundamental will be playing later.

Edwin Linton, formerly a sergeant major in the Scots Guards, is standing around in a fluorescent vest; he has been camping in the square for 23 days to protest at the lack of compensation for veterans with Gulf War syndrome.

He peels back his gloves to show the sores on his hands. “I’m very bitter.

And it makes it worse, thinking about the poor lads who’ll be coming back with the same thing.”

About 60 teenagers have gathered in the square, some of the girls in fairy wings, feather boas and face paint. The boys are in hoodies, sporting peace badges on their rucksacks, with loud voices sliding up and down the register. They’re serious about the cause. Thirteen-year-old Rosie Packton - who cheerfully tells me this is not her real name, is from Pimlico school, where Foreign Secretary Jack Straw was a parent and governor. “I want this war to stop. I don’t think innocent people in Iraq and children like us should be dying,” she says. “They should have negotiated it through, not bombed people.”

Pimlico, she says, has been “firm but fair” regarding student walk-outs, with an hour’s detention for the first one and the threat of a referral for subsequent ones. “Shh,” says Nadine, holding tight to her oboe case.

“You’ll give the school a bad name.” Is it a good party? “I’m very cold,” admits Rosie.

The low sun picks out the gold leaf on Big Ben; police officers are reading the Evening Standard in their white van, feet up. There’s a scanty stall where Socialist Worker is on sale, a smell of weed drifting on the air and a gathering on the other side of the square organised by a women’s centre in north London, promoting “caring not killing”.

Henna Malik is a student of politics, English and drama at Coombe girls’

school, an independent in the London borough of Kingston upon Thames, and one of the organisers of School Students Against the War. Eight thousand young people were expected here today. Are school students still against the war? “This isn’t a war of liberation. We’ve seen Ali with his arms blown off and we’re trying to show we stand in solidarity,” she says, blaming the weather for the poor turn-out.

The police rule that no music can be played, because Parliament is sitting.

An adult from the Stop the War Coalition gets up on the platform and announces through a PA that George Galloway sends his apologies. “He’s been called away to do an interview with Abu Dhabi TV and he says hello.”

“Tony Tony Tony, out, out, out,” she calls, instead. Lindsey German tests the young people’s concentration span. “I haven’t seen a single statue pulled down by the Iraqi people,” she says. The feeling is, the kids here, and everywhere, deserve better.

Then one of them - Sinead Kirwan from the LaSwap sixth form consortium - gets up on the platform, blue with cold, and makes an impassioned speech.

“If we’re old enough to sit Sats, to take GCSEs and A-levels - which are going to affect us for the rest of our lives - we’re old enough to protest against a war that is definitely going to affect us for the rest of our lives.”

I have promised not to speak to my son. But when one of his friends comes up to ask me for a tissue, Dan seems to feel the game is up. Is student protest over? “If another potential situation were to arise, I think we’d take more action.” He’s thinking of leaving now, him and his friends. “Is there anybody in at home? Is there a free house?”