So what happens now?
What was not so long ago unthinkable has come to pass. Now the hard work really begins – both for the Labour Party and British Jews.
Jeremy Corbyn’s election as leader will raise tough questions about the future of the relationship.
After five years of the deeply damaging, fractious life with Ed Miliband, many in the community will see his successor as someone who they are even less likely to be able to work with.
Three weeks ago, seven in 10 British Jews told a JC poll they were concerned about the prospect of Mr Corbyn as leader, with more than 80 per cent worried about his potential foreign policy positions and links to Holocaust deniers.
How far both sides will now go to patch things up is unclear. But neither is likely to be willing to take great strides in the early stages.
Rumours emanating from the Corbyn camp within the last 48 hours suggested he wanted to appoint a “Minister for Jews” – an emissary to work with the community. Is that a proposal that is likely to help?
While apparently designed as a measure to improve relations and build bridges, unveiling religion-specific portfolio holders – there would also be a Minister for Muslims it is understood – could be yet another PR disaster for the 66-year-old leader.
Would he, for example, give the Jewish minister job to a Jew? Or would it go to a non-Jew who was friendly towards the community? What about a Jew who was unfriendly towards the community? It would be a minefield.
Could left-wing veteran Sir Gerald Kaufman – now the Father of the House and 85 years old – be dispatched? He’s a Jewish MP who caused outrage in the Commons by declaring “here we are, the Jews again” when colleague Louise Ellman rose to speak. Another fine mess Mr Corbyn could get himself into.
The wider intentions for the years to come should be easier to decipher within the next few weeks. His shadow cabinet appointments will give the clearest indication of how far to the left he wants to take the party.
Senior roles for veteran left-wingers, such as Diane Abbott, would be one way of setting out his stall.
There would be further worries for Israel supporters if key backers from past shadow cabinets, such as Tristram Hunt, were lost from Labour’s frontbench.
But were Mr Corbyn to take steps back towards the centre and somehow convince his defeated rivals Yvette Cooper and Andy Burnham, and other former ministers, to bring their government experience, some conciliation may be possible.
Meanwhile there could be huge pressure on veteran MPs such as Ivan Lewis – another former minister – and Britain’s youngest Jewish MP Luciana Berger. Both are ambitious and would, under other circumstances, give a their right arm to have another shadow position. But could they work for Jeremy Corbyn? It is hard to see how.
On the policy front it seems inconceivable that he could pursue what have in the past been fringe issues – such as Palestinian statehood – ahead of other more pressing matters such as the economy, NHS and education. But this is a step into the unknown in so many ways.
Foreign policy will clearly be one of the key sticking points. Campaign comments and decades of campaigning suggest the Islington North MP will adopt a hardline approach to Israel, possibly pushing for sanctions, boycotts of settlement goods, and even stronger efforts towards Palestinian statehood than those made by Mr Miliband.
In the event of another Gaza conflict it would take little to whip up the public fervour further still. Mr Corbyn would be in his element, and in this respect the picture would look bleak from the community’s perspective. He could be expected to enjoy substantial support on the streets.
But how far would he get in the Commons with anti-Israel proposals, when so many in the parliamentary Labour Party seem destined to refuse to back him on a wide range of issues? With so few of his own MPs willing to support his leadership, Mr Corbyn and Labour could face total paralysis.
Speculation in the past fortnight has included the prospect of rebellious MPs seeking to dethrone him almost before he has started work. How long he will serve as leader is a question which will be asked continuously from today. A reasonable estimate would suggest Mr Corbyn can look forward to a minimum of eight months in the role, taking the party up to next May’s local elections and London Mayor election.
But if the new leader stays in his position until May 2020, with no alteration of his previous views and positions, the damage done to the Jewish community’s relationship with the Labour Party could be terminal.
Following months of unprecedented interest in the leadership contest, Mr Corbyn’s election marks merely the end of the beginning. Whether it is the beginning of the end for Labour remains to be seen.