Parliament Square can have seen few stranger outpourings of emotion than the demonstration on Monday evening where many hundreds of Jewish members of the Labour Party told Jeremy Corbyn “enough is enough”, and called on him to take decisive action against anti-semitism.

For Corbyn to have angered and distressed so many loyal, decent, well-behaved members of his own party looked like a disaster for him.

They expressed the mourning and sense of betrayal of people who cannot believe what has happened to the party in which they put their faith. They are patient, but for Corbyn can find no more patience, though even in their anguish they continue to demonstrate their faith in the power of peaceful protest and argument.

The sun was sinking behind the Supreme Court at the end of a perfect afternoon, and many from beyond Labour’s ranks had come to show solidarity.

Sajid Javid, the Secretary of State for Communities and Local Government, was there, and told ConHome: “I feel very sad about it. It’s very sad that in 2018 the Jewish community must come to Parliament Square to protest against anti-semitism in a major political party.”

Jonathan Arkush, President of the Board of Deputies of British Jews, told the crowd that the last two years “have felt like a daily assault on our Jewish community”.

He welcomed the many Labour MPs who had come to support the demonstration, including Wes Streeting, Luciana Berger, Louise Ellman, John Mann, Chuka Umunna, Joan Ryan, Ian Austin, Ruth Smeeth, Mike Gapes, Stella Creasy, Chris Leslie, Margaret Hodge and Liz Kendall.

Arkush said: “Time and time again Jeremy Corbyn and those close to him have failed to back meaningful action against anti-semitism.”

Two years on, after “a limp inquiry lacking any credibility”, Ken Livingstone had not been expelled from the party – an observation which drew cries of “Shame!”

“Enough is enough,” Arkush went on. “It’s not good enough.” He had never known “such anger in our community against a mainstream political party”.

“Finally, finally, Jeremy,” Arkush pleaded, “take some responsibility.”

“Where is he?” a demonstrator shouted. Corbyn was across the road in the House of Commons, about two hundred yards from where the demonstration was taking place.

It seemed a craven evasion of responsibility that he had not found the time to cross the road and assure these devout Labour supporters that he was on their side.

John Mann, MP for Bassetlaw, addressed the crowd, and asked: “What on earth is going wrong with our party when this kind of event even has to be considered?”

Wes Streeting, MP for Ilford, said anti-semitism was “a stain on the conscience of the Labour Party” and “a gross betrayal of everything the Labour Party has ever stood for”.

Red buses drove past, from which tourists, distracted from such masterpieces as the Houses of Parliament and Westminster Abbey, took pictures of the curious gathering.

“We do not need any more mealy-mouthed statements from the Leader of the Labour Party,” Streeting said.

Sid Rutstein was a Liberal Democrat councillor until losing his seat in 2011. “I was going to go to the pictures this afternoon”, he told ConHome, but instead he was attending the demonstration in order to show “support and solidarity”.

“I’m a member of the Board of Deputies – I represent Luton Synagogue. A friend of ours was involved in a film and a book following the Chakrabarti report on anti-semitism in the Labour Party.

“It was called Whitewashed, and what it demonstrates is that there was information given to the Chakrabarti inquiry that was not included in the report.”

Daniel Finkelstein, a Conservative peer and journalist, said of the event: “This is so depressing this is necessary.”

Corbyn’s admission “that anti-semitism has happened within pockets within the Labour Party” had prompted a home-made banner which read “Corbyn is the pocket”.

A small pro-Corbyn counter-demonstration, carrying banners bearing such messages as “Jews for Jez”, had gathered in the corner of the square under Churchill’s statue.

“You should be ashamed of yourselves,” someone in the main demonstration shouted, and began a chant of “Shame on you”.

But the small counter-demonstration faded into insignificance once the main event was under way. What depths of alienation from the Corbyn leadership were here laid bare.

One may ask what the Labour MPs who consider him unfit to be Prime Minister will do next, but must also wonder why Corbyn wants to carry on.