More than a million Labour votes — 98 per cent of those eligible — overwhelmingly approved a rule change in the party’s constitution which will enable it to deal better and more swiftly with those expressing bigotry, hatred, and anti-Jewish views.

But the debate about the rule change — a campaign initiated by the Jewish Labour Movement and endorsed this year by both party leader Jeremy Corbyn and the powerful National Executive Committee (NEC) — took place on the conference floor in a toxic atmosphere in which speaker after speaker denounced it as an attempt to stifle criticism of Israel.

The change, on “conduct prejudicial to the Party” will make it easier for Labour to expel members whom it considers to have breached this rule. But angry hard-Left anti-Zionists, at least two of whom were Jewish, furiously attacked the JLM for its campaign. Leah Levane, from Hastings and Rye Constituency Labour Party (CLP), said her branch, which had tried to amend the proposed rule change, had been put “under intense pressure by the NEC,” which, she said, had “clearly negotiated with the JLM”. Angrily, she told the conference: “They [the JLM] do not speak for me”, and claimed that accusations of anti-semitism arose “every time you criticise the despicable behaviour of the state of Israel”. She received a standing ovation for her remarks.

But the JLM’s deputy leader, Mike Katz, said the purpose of the rule change was “to close off a loophole, a cop-out clause which says holding a sincerely held belief makes hate speech okay.

“Come on, Conference, is it really okay for a member to say they’ve got a sincerely held belief that women are inferior to men, or that the Holocaust didn’t happen? No, of course not.

“We want to see anybody saying that kicked out on their ear…This rule change is about so much more than just anti-semitism. It’ll give us the power to put a stop to the misogyny, the homophobia, the racism that can creep into our party.

Mr Katz declared: “There is nothing wrong about legitimate criticism of the Israeli government or illegal settlements. JLM members do it all the time, often in strident debate — but you don’t need to use anti-semitic language and stereotypes to engage in that debate and that’s what we need to deal with.”

Councillor Phil Cohen, from Finchley and Golders Green CLP, told the Conference that “too many Jewish voters in Barnet turned away from Labour because they saw a perceived inability to deal with the anti-semitism issue”. Potential seats were being lost to the Conservatives because of this, he said, and urged delegates to vote for the rule change.

But an angry Sara Kellaway, from Hampstead and Kilburn CLP, adapting Labour’s slogan of “for the many, not the few”, said the whole issue was about support for the Palestinians. “We have to stand with the Palestinians, who are many, and we have to stand with them. We cannot be a party that has groups which support an apartheid state, wherever that is”.

By this stage of the debate some Jewish Labour members were tweeting their distress and discomfort at being in the hall. Izzy Lenga, who has faced antisemitism in the National Union of Students, wrote: “I didn’t think it was possible, but I feel a whole lot more unsafe, uncomfortable and upset as a Jew on the Lab17 conference floor, right now, than I do at NUS”. Marlon Solomon added: “So depressing being Jewish at the Labour conference. Leaflets calling for the expulsion of JLM. We’ve been affiliated for 97 years”.

But it was a speech by Chingford and Woodford Green CLP’s Naomi Wimborne-Idrissi, a prominent Jewish anti-Zionist, which drew the loudest applause. She sneered at JLM, saying they would be “a lot more credible if they didn’t run to the Daily Mail and the Daily Telegraph with stories”, a claim immediately rebutted by the Telegraph’s Jason Groves, who said: “Nobody ‘ran’ to us. We just reported anti-semitic comments at Labour events, including an unpleasant one chaired by Naomi herself.”

Ms Wimborne-Idrissi, one of the founders of the new group, Jewish Voice for Labour, said that they were no longer the “alternative Jewish view, I think we are the mainstream now.” And she derided the language of the rule change for referring to people “holding opinions” — shouting: “That’s thought crime, comrades, and we can’t have that”.

In such an atmosphere it was hard to see how the JLM campaign for change could succeed. But the vote was a card vote rather than a popular show of hands — and the rule change had the backing of Jeremy Corbyn and the majority of the unions.

Simon Johnson, chief executive of the Jewish Leadership Council, welcomed the rule change, but advised caution. He said: ““The JLC welcomes the Labour Party’s rule change on antisemitism and hopes that it will be backed up by firm action”.

He was echoed by the Board of Deputies chief executive, Gillian Merron, herself a former Labour MP. Welcoming the vote, she said: “This is particularly important after the ugly scenes we have witnessed during this conference and shows the need for resolute and robust action.

“However, in order to judge the success or otherwise of the new rules, we will be watching for the results. Will those who have maliciously questioned the historical record of the Holocaust, those who have engaged in anti-Jewish conspiracy theories, or called for Jews to be purged from Labour, still be welcome in Labour, or will they be thrown out as they so obviously should be?”

Amid allegations that accusations of anti-Semitism had made Labour the “nasty party”, Jeremy Corbyn said it was “awful” for anyone to brand Labour with that term. “This is not a nasty party,” Mr Corbyn told Channel 4 News. “This is the biggest Labour conference we have had for many, many years. “Nobody should be abused, whoever they are. We have just passed a motion on racism and anti-Semitism which is comprehensive and inclusive and is supported by all wings of the party and unanimously agreed by our national executive.

“Anyone using anti-Semitic language, anyone using any form of racist language, is completely at odds with the beliefs of this party.”