On Saturday, about half a million people took action in response to the coalition government's public-sector spending cuts. This is how I witnessed it.
The largest group disrupted traffic across a large section of central London as they marched from Embankment to Hyde Park, chanting slogans, banging pots and pans and blowing whistles and vuvuzelas. The cost of the damage caused by people littering and tramping across the grass in one of the country's best-loved public parks is yet to be assessed.
A much smaller group, perhaps of around a thousand, staged sit-ins at a number of West End shops in the early afternoon. This was followed by a rally in Soho Square, where campaigners were entertained by stand-up comedians and a well-known newspaper columnist. They then staged a final, peaceful sit-in, en masse, in the upmarket grocery store Fortnum & Mason. These people were arrested on leaving the shop, kept in the cells overnight and charged with aggravated trespass. (This illiberal law was introduced in 1994 as part of the widely opposed Criminal Justice Bill, and can be applied to anyone who "trespasses on land with the intention of disrupting, or intimidating those taking part in, lawful activity taking place on that or adjacent land".)
A smaller group still (the BBC's Paul Mason estimates 600) smashed the windows of and threw paint at shops and banks in the West End. From what I saw, there was no serious attempt to arrest those causing the damage.
There are two lessons that I think the anti-cuts movement (by which I mean anyone who turned out on Saturday) should take from this. First, there has been a great deal of sneering among advocates of "direct action" in the past few months at "A to B marches". I hope Saturday's march, which left me feeling exhilarated and hopeful for the prospect of building sustained opposition to the cuts, proves that bringing together a huge cross-section of society is valid and necessary action. Of course it doesn't change anything in isolation, but just think about how many people returned to their workplaces today, sharing their experiences with colleagues, realising that they're not alone in their fight and, with any luck, thinking about what to do next.
Second, there is a narrative developing among some sections of the left that UK Uncut wrecked Saturday's protest by diverting attention from the rally in Hyde Park and is somehow responsible for the "anarchist violence" focused on by most of the media. This plays into the hands of the right and needs to be stopped.
Had UK Uncut not been present, the property damage would have happened anyway, and the media still would have focused on it. Moreover, it's wrong to assume that anyone who took part in direct action is also a committed anti-capitalist. Some may be (as are some Labour Party members, and plenty of others who attended the official demonstration), but UK Uncut's central message – that corporations should pay their fair share of tax – is entirely compatible with a social-democratic movement. Nor is it one that alienates large numbers of voters.
Labour should be asking itself why the thousands of people who have taken part in UK Uncut actions since the autumn don't see the Parliamentary Labour Party as the best route through which to enforce a fair tax system. (Is it, perhaps, because Labour while in government proved unable to stop banks and corporations ripping off the state?)
There may be an argument about tactics, which all sides of the movement should consider. Was Fortnum & Mason the right target? Should the sit-in have taken place at the same time as the main march? But the outright hostility and disdain directed at UK Uncut from elsewhere within the left is damaging to the movement. As one Labour councillor I know (who is from the centre left of the party) said to me today: "I can't understand why some Labour people are so proprietorial about peaceful protest – perhaps it speaks to a wider insecurity about our role in opposition."
This morning, David Cameron issued a statement saying that those responsible for the damage on Saturday "need to be dealt with and to feel the full force of the law". It is imperative that those with the power to do so speak out in support of the UK Uncut protesters and make sure they are not collectively punished for the actions of others.