It began, fittingly, with an announcement about how to get out.

“In the event of an emergency,” the Rabbi of Western Marble Arch Synagogue in central London told the 250-strong crowd, “please evacuate the premises.”

It was fitting because, after all, those present at the Extraordinary General Meeting of the Jewish Labour Movement, called after its parliamentary Chair, Luciana Berger, quit Labour calling it "institutionally antisemitic" - were discussing whether to leave the party after a 99-year affiliation.

As we filed in to the Sanctuary, one person joked about us being here for a barmitzvah. At times, it felt more like a funeral.

Before the debate, three Jewish Labour MPs - Dame Louise Ellman, Dame Margaret Hodge and Ruth Smeeth - addressed the audience.

All three spoke with frankness. Dame Louise called this “a fight for the soul of the Labour Party”, and said: “A party that allows antisemitism to go unchecked is not a anti-racist party.”

She was also unambiguous about the Labour leadership.

If JLM decided to leave Labour, she said, “despite the letter of so-called support from Jeremy Corbyn, they’d actually be raising their glasses.

“You know who else would be happy? JVL.”

It’s hard to over-estimate the strength of feeling about Jewish Voice for Labour, a group on the fringes of the Jewish community that seems to exist solely to deny the extent of Labour's antisemitism problem.

Even before the meeting, there was the strong sense this was a key reason people would vote for JLM to remain affiliated. As Dame Margaret said: “I don’t want to be in a position where I’m a Jewish Labour MP, with JVL representing Jews in the Labour Party.”

She also described how, for Labour Parliamentarians who “have been fighting the growing cancer of antisemitism, it sometimes feels very lonely... I can’t tell you how much it has meant to have the JLM behind us.”

Dame Margaret said that, even when she took on Nick Griffin, the leader of the far-right BNP, in her Barking constituency at the 2010 general election, she only received a fraction of the antisemitism she has received since Corbyn became Labour leader.

She made clear her intention to stay in Labour. 

“I fought the fascists on the Right, I will fight the fascists on the Left.”

While the London meeting was going on, another JLM meeting was being held in Manchester, where people could watch the MPs' speeches as they were live-streamed.

While Ms Smeeth was speaking in London, her mother was in the Manchester audience.

The Stoke on Trent North MP described how “for three years I have begged Jeremy Corbyn to do something about this”, to no avail. 

Part of the reason it was so important to her to stay, she suggested, was because of the 14-year old girl. The girl who is interested in politics, wants to be involved in politics - but feels she can’t, because she’s Jewish.

If she was that 14-year old girl again now, in the current climate, Ms Smeeth said, she would not want to join Labour.

Two more MPs, Ian Austin and Wes Streeting, were in the audience. Both have been vocal on antisemitism and Mr Austin quit Labour last month.

After the three MPs spoke, the debate began.

It was emotional - and private. The Jewish Labour Movement requested directly that any members of the press present who had attended as JLM members not report the comments made during the debate, to allow everyone to speak freely.

But what it did bring home was the situation some JLM members have experienced in their local Labour parties. The waves of abuse from many other members - and support from a few. The feeling of helplessness in the face of hatred. Some who had taken the decision to leave the party spoke movingly about why they had done so.

There was a lack of any sense of judgement, from those who had left towards those who have stayed, or vice versa. Everyone acknowledged the incredibly grim circumstances.

Part of the irony here is that in terms of its membership figures, the JLM is the largest it has been in decades. As JLM National Secretary Peter Mason said, every time there has been a particularly egregious deterioration in the relationship between Labour and UK Jews, there has been a surge of people joining.

When Labour failed to expel Ken Livingstone, for example, 500 people signed up. And at Wednesday's meeting I sat next to a young Jewish man, a “Labour member for many years”, who said he had decided to become a JLM member two weeks ago, after having seen Luciana Berger effectively driven out of the party.

The indicative vote at the end was not surprising- a show of hands revealed well over 80 percent in favour of JLM continuing its affiliation to Labour. But it seems highly likely that there will be a significant hardening of the organisation’s stance.

Serious discussion will need to be had, for example, what to do in the event of an election; the notion of campaigning in any way to help Jeremy Corbyn into Downing Street is now unpalatable for many.

As Mr Mason said at the end of the evening: “We have a simple message to the Labour Party, its Leadership, its MPs, its councillors. If you do not show solidarity with us, we will not show solidarity with you."