With military action now almost certain, Britain's anti-war movement faces an urgent challenge: how to follow up the biggest demonstration in British political history. Alistair Alexander reports from London One month ago, between one and two million people from across Britain gathered in freezing weather conditions for an unprecedented display of opposition to war in Iraq. But despite the sheer scale of the protest, British Prime Minister Tony Blair has stuck doggedly to his hard-line support of military action against Iraq. The march had a big effect, however. "It enormously extended the reach of the movement," says John Rees, one of the founders of the Stop the War Coalition. Rees believes the march may even have affected the government's military timetable. "I think, apart from anything else, the war would have started without that demonstration." Since then Stop the War has organised a march of school students to Downing Street and a number of demonstrations across the country for International Women's Day on 6 March. On Wednesday, 12 March Stop the War held a Peace Assembly in Central Hall, Westminster, opposite Westminster Palace, where 3,000 delegates from local groups issued a call to action for the movement. As the crisis over Iraq escalates into a crisis of legitimacy for the Labour government, the Peace Assembly is intended to be a direct challenge to parliament. Central Hall is a venue steeped in symbolism; the first meeting of the United Nations was held there in 1945. "The institution itself will be a standing condemnation of the lack of democracy across the road," says Rees. Rees is also hopeful that mass strike action is on the cards. After years on the political margins, Britain's resurgent trade unions have been a key factor in the strength and depth of the anti-war movement. "I think it's a question of getting the momentum going, but there are signs that that's beginning to happen quite quickly," Rees notes. But calling for another mass march like that of 15 February poses a problem for Stop the War, as any perceived drop in numbers would be seized by the government as proof of a movement in decline. So far Stop the War has called for action at local town halls and civil disobedience on the day war breaks out, as well as another large rally the following Saturday. But, with a proposed deadline on 17 March for Iraqi compliance, Stop the War is "pencilling in" 22 March for the next big national rally. For many of the marchers -- a huge number of whom had never protested before -- the rally on 15 February drew as much frustration as it did inspiration. If such a large number of people does not stop the war, what will? Inevitably, the focus is shifting towards more direct methods of protest. Former Labour MP Tony Benn is clear about the future direction of the anti-war movement. By ignoring the views of the overwhelming majority, he argues, the government has "liberated us from the normal restraints we take upon ourselves". "And what we do with that freedom is very important," he adds. "It's got to be non-violent action according to your conscience." Whereas the Stop the War Coalition has drawn on the long- established political networks of the traditional left, direct action is harnessing the energies of the more nebulous anti- globalisation movement. "Disobedience" -- a loose affiliation of anti-war activists -- reports actions on a daily basis. Many are virtually spontaneous -- hastily arranged via e-mail and SMS. On Monday, at 8am, a small but noisy crowd were banging drums outside a discrete London defence conference attended by Defence Secretary Geoff Hoon. Hoon barely attends a meeting these days without loud hailers, boos and whistles on hand to welcome him. At RAF Fairford, where B-52 bombers arrived last week to fly missions to Iraq, the "Gloucestershire Weapons Inspectors" have established a "Bomber Watch". Armed with "smart bomb intelligence detectors" and "collateral damage anticipation indicators", the inspectors have tried several times to "inspect" the base for weapons of mass destruction. Disturbingly, however, their inspections have been continually obstructed. Nevertheless, chief weapons inspector, Dave Cockroft is upbeat about what the weapons inspectors can achieve. "There's a lot of very determined people around," he says. "Previously, groups managed to get onto the airstrip in the Kosovo war and prevented the take-off of the bombers." Actions at military bases are certain to increase with a national "Reclaim the Bases" day on 22 March. At Men with Hill in Yorkshire -- a key US surveillance centre -- a "Foil the Bases" protest is planned, where protesters will bring foil balloons, costumes and kites to disrupt radio signals. Other bases will be subject to large actions. With regard to specific acts, most activists are unsurprisingly tight-lipped. But many take heart from a legal decision in 1996 where an activist was acquitted of causing criminal damage to a Hawk fighter plane. The plane was to be delivered to Indonesia, but the activist was judged to be acting for the greater good. For most activists the most unexpected development of the protest movement is the extent to which it has broken through to mainstream politics. Up until two weeks ago, dissent over the government's position in the House of Commons had been negligible, with the conservative opposition vigorously backing the prime minister. Last week's vote in the Commons -- when 122 MPs voted against the government in the largest Commons rebellion for over a 100 years -- suggests that Labour MPs are making up for lost time. The government's massive majority of 170 ensured the result was not in doubt, but the action was a massive shock to the government and suggested the once awesome command Tony Blair held over his party had all but disappeared. "He put a huge effort into trying to stem the rebellion but to no effect," recalls MP Jeremy Corbyn, a founding member of Labour Against the War. "The shattering of consensus in the Labour Party was because a mass movement slammed into the side of it that can mobilise two million on the streets," says Stop the War's Rees. Over the weekend a number of government aides threatened to resign if Blair failed to secure a second resolution. The challenge was swiftly followed by an unprecedented personal attack by Cabinet Minister Clare Short, who called the prime minister "extraordinarily reckless". Even more remarkably, the prime minister felt unable to sack her -- humiliatingly underlining his rapidly diminishing authority. As a second resolution looks increasingly unobtainable and with a further Commons vote on Iraq later in the week, Mr Blair's position is threatened as never before. If many protesters were disappointed with the initial impact of the march on 15 February, the aftershocks look set to reverberate around Westminster at ever more resonant frequencies.