When one person makes a complaint, it can mean nothing. But when two people come to you with one story on one day, it is worth listening.  

I spent all day yesterday at the SWP's annual event Marxism. It is an annual celebration of the international left: speakers come from all over the world, around five or six thousand people attend. The numbers seem to have been slightly up on last year, although there were one or two meetings which have felt small. Several of the speakers pulled out in the aftermath of the bombings - not out of hostility, but from an unwillingness to be in London, so soon after the bombings. Rose Gentle, for example, wrote on Thursday saying that she wouldn't not be able to attend; before changing her mind and traveling down two days later.

The event has at times been muted. Taking place just minutes from Tavistock Square, and near Euston, there are policemen, film crews everywhere. Posters calling for revolution sit awkwardly beside others showing pictures of young students partying, in the very flush of youth, and asking 'have you seen my friend?'.

Most of the day I spent talking to an Israeli journalist, who I will call 'Leah'. She introduced herself to me as an Israeli supporter of the one-state solution. We talked about the campaigns she's led, to support Palestinians whose lives have been destroyed by the 50-year occupation, the documentation of the crimes of the Israeli army, the tendency of people in Britain to exaggerate the importance of the visibly racist settlers and to miss the patient brutality of mainstream Israel. 

But what Leah really wanted to ask, was about Britain: is there any space left for a specifically Jewish radicalism in this country? 'Lots of my friends tried to get involved in the Stop the War coalition. They are liberal people, whose values are close to those of the British left. They came on the demonstrations, but didn't feel welcome. They then attended Jewish events, which hardly spoke to them at all.' 

'I also know other people, Jews who opposed the war, but who are older, more middle-class. They heard such terrible untruths about the movement, they thought there would be swastikas all over it. They didn't want to take part. The anti-war movement seems to make such an effort to encourage Muslims to take on roles in the leadership - but no-one makes the same effort with left-wing Jews. Where are the prominent anti-war Jews?'

'Isn't the movement showing once again, its old hostility to the Jews?'

I tried to show that there are prominent figures in the anti-war movement who are indeed Jews: Mike Rosen, Mike Marquese, John Rose. I talked about the ways in which people had challenged certain behaviour on the marches. I also mentioned that Jewish papers had been approached, and people asked to report the movement fairly, on its own terms.  

I argued that people misunderstood the movement's relationship with anti-war Muslims, who have not simply been recruited on a communal or religious basis, but in a dialogue with the left, and as a break with previous forms of Muslim political organising: against for example the people who leafleted the marches saying 'don't march with non-Muslims'. What was true for Stop the War was also true of Respect. The highest Respect votes came in constituencies were all the other candidates were often Muslim, against them, Respect didn't say 'we are better Muslims' but argued instead for a socialist politics based on the interests of the poor. 

I argued that the central question of the day was the war and the rise in racism that followed it - that there are people like Christopher Hitchens whose ideological background equally 'should' have made them allies of the movement, except that they parted company with it. The movement was necessarily an anti-war campaign: it has attracted people who were resolutely anti-war, and lost those who have equivocated.

I asked whether you could base an anti-war sentiment consistently on Jewish identity politics? Hasn't Israel so consumed so much of what it means to be a Jew, especially a secular Jew, that the opportunities for left-wing Jews to organise as such, has been narrowed almost to nothing? In the same way that a left-wing men's movement is always fragile, and liable to implode; aren't there equivalent problems with trying to reconstruct a Jewish left-wing politics? Susan Faludi shows in her book Stiffed that capitalism distorts male sexual identity and oppresses many men as men. Men aren't monsters, but inequalities of power oblige us to approach the social movements as people, without a specific male identity of our own.  So too for Jews. My own answers didn't satisfy me, which is why I repeat them here. 

What struck me most, came a few hours later. I was leaving a meeting, speaking to someone else who I had only met for the first time that day, a well-known veteran of the black liberation struggles of the 1970s and early 1980s, someone who has been put on trial for organising self-defence campaigns, a novelist and film-maker, a Muslim who spent most of that period working with young radical Sikhs, whose parents were Communists, atheists, and supporters of the Indian Workers Associations.

He turned and said to me, 'Why does the movement only talk about Muslims? There are Sikhs, dying out there, and nobody speaks for them. The anti-war movement is doing such damage.' We began to talk; there wasn't time. His questions reminded me so much of Leah's.

This morning, the papers were reporting a number of racist attacks since Thursday's bombs - on at least three mosques, and on the Sikh temple at Gravesend. The Muslim Council of Britain has had to close its email system, while clearing through backlog of 30,000 hostile messages. 

The cutting edges of present-day racism are undoubtedly anti-Muslim and anti-asylum hatred. But this joint campaign, now of several years' standing, has affected the ways in which every black and first- or second-generation migrant lives. People who have lived in Britain for fifty years feel under greater pressure almost than ever before. Friends ask, could we live anywhere else? 

The new racism is both old and new. It may take different forms, but it also reinvigorates older ones.