Jon Lansman talked to Solidarity.

You've said that the concern about antisemitism in the Labour Party is based on realities, not something contrived or invented. Why do you say that?

Because I've seen loads and loads of cases at the National Executive, and I know them to be real. I also know that those cases are very rarely to do with Israel-Palestine.

I also have plenty of evidence on my own social media, although I try not to look too much at that because it is so unpleasant. I follow the advice of many others who get abuse on social media, and try to ignore it.

In short: the evidence of my own eyes.

Are you surprised by this development?

I have been surprised at what appears to be a continuing and increasing problem. The whole debate is toxic for the Labour Party and for the left.

The fact that there are so many people who deny the problem, or say it's all inflated by people who are hostile to Jeremy Corbyn or to the Palestinians, that draws more of the problem out into the open.

The surveys show that between 2.5% and 3% of the population in Britain are antisemites, and about 30% have one or more antisemitic prejudice. Those are the lowest figures in Europe, but that only means it may be worse elsewhere.

You may expect the percentages to be less in the Labour Party, but by how much?

Doesn't the fact, as you mentioned, that so many people in the Labour Party say that the concern about antisemitism is all, or mostly, driven by people who are hostile to Jeremy Corbyn or to the Palestinians, or want to cover up for Israel, make a big difference here? Where other prejudices tend to get suppressed in the Labour Party because people know their expression will be condemned, antisemitic prejudice is more licensed.

Most people deny whatever prejudices they have. That is why we send people on training courses - to make them aware of the prejudices they have.

Some people have conscious prejudices. Most people have unconscious prejudices too.

The fact that concerns about antisemitism are dismissed in that way does make a difference.

Sometimes that problem is based on ignorance, sometimes on prejudice.

Momentum has done some work on this - released three or four videos, recommended Steve Cohen's book...

We intend to carry on that work. We are developing further educational and training materials. We're going to develop more videos. We see that as political education. We've been training our staff.

We kicked all this off with a statement against antisemitism which was seen as very strong.

We obviously are aware that there is opposition to this from amongst sections of our membership.

We've argued that open face-to-face debate is necessary too, and we think the narrowing of the channels for debate within Momentum make that necessary work harder...

There can be discussions in local groups. There has been no reduction in the level of discussion in local groups, though of course they go through periods of thriving and periods of doing less well.

We certainly have discussions at the national level too. But in the old regional structures you wouldn't have been able to have a discussion because it was very polarised.

There is a generational element here. The generation of people who are in their late 40s or older have a worse response. It's not a matter of age, but of different experiences.

We get a much better response among younger people. Younger people can be just as militant about Palestinian rights, but better on antisemitism.

You've done work with Standing Together, a left-wing Jewish-Arab peace group in Israel. Can that sort of work make a contribution here?

Standing Together do fantastic work not only on Palestinian rights, but on the deportation of African refugees, on LGBT rights and on economic issues. Practical examples of Jews and Arabs in Israel-Palestine working together are absolutely beneficial in trying to find common ground in opposition to all forms of racism, including antisemitism.

They foster some recognition of permitting people to express national rights, of a more multicultural approach.

In spite of the fact that there is still extremely wide support for, at least lip-service paid to, "two states" as the best way of achieving peace in Israel-Palestine, there is in many circles in the Labour Party very little acceptance of the right of Israel to exist. That is a problem.

Acceptance doesn't have to be based on Zionist ideology as such – Israel’s creation was a decision of the UN in the face of the plight of Holocaust refugees. I'd say that we live in a post-Zionist age. Israel is a major military power and will carry on existing. To achieve peace, a two-states solution remains the best prospect.

At present, especially with Trump, there is little prospect of any peace solution in the near future.

Zionism is a word which means different things to different people. There are sections of the Labour Party who can only see Zionism as an ideology, and as a monolithic ideology.

In fact Zionism has always been a set of ideologies - Labour Zionism, General Zionism, religious Zionism, revisionist Zionism, binational Zionism... but many British Jews do not see it as an ideology at all.

Zionism acquired a majority in the British Jewish community only in 1939. And it only really took hold, I think, after the Six Day War of 1967.

That was when British Jews started visiting Israel more, emigrating more, having more relatives in Israel. When I was a kid in the 70s, I went to work on a kibbutz.

Labour Zionism was then dominant not only in Israel, but also in the British Jewish community, and the links to the kibbutzim were very important.

Israel has had a very big political shift since then. Israel is now a neoliberal country, and the roots of Labour Zionism have been more or less cut. Labour Zionism is actually stronger in Britain now than Israel. Not so strong in the USA, but you have more secular Jews there.

Today, 6 March, the Jewish Labour Movement (JLM) is meeting to discuss possibly beginning proceedings to disaffiliate from the Labour Party. What do you make of that?

I'm sorry not to be there at the meeting. I'm not a member, and I don't subscribe to all the views of the JLM, but they are the strongest voice for the Labour Party in the Jewish community, and they represent the mainstream community in the party.

I very much hope that they won't disaffiliate, and if they do, I would hope it won't be permanent.

We are now at the point that I'm aware of left-wing Jews - people who supported Jeremy Corbyn in both Labour leadership elections - who have decided to leave the Labour Party, or have already left. What's happened has affected left-wing Jews too.

Of course it may be easier for Jews opposed to Corbyn's leadership and the Corbyn project to leave the Labour Party but I'm sorry that anyone is going to leave the Labour Party over antisemitism.

There's a distinction between Luciana Berger and the other MPs who left the Labour Party recently. Her rationale was antisemitism, and I think that wasn't really true of the others.

But it's a tragedy that anyone should leave the Labour Party over antisemitism.