When I was a student in the mid-1980s I was endlessly impressed by many of the Jews I worked alongside to stop the far left banning student Jewish Societies. I could claim it was because they were all smart and funny, and many were.

But if I am honest it was also because they were willing to fight. I can recall Adrian Cohen, otherwise a very gentle man, squaring up to a guy who had called him an antisemitic name at an NUS conference, and threatening to bury his “Jewish fist” in his face. How could a Suedehead from North Shields not be impressed with that?

I hope I have brought that combination of intelligent argument and fighting spirit (if not actual fists) to Institutionally Antisemitic: Contemporary Left Antisemitism and the British Labour Party, a 30,000-word Fathom report I have written, which was launched this week in the House of Commons with the help of Karen Pollock of the Holocaust Educational Trust, Dave Rich of CST and my old university friend John Mann MP.

After a review of more than 130 examples of antisemitism, antisemitism denial and victim-blaming, the report makes two claims about Labour today.

First, that the party can now reasonably be described as “institutionally antisemitic”, according to the precise definition offered by the 1999 Macpherson Report. Perhaps tomorrow will be different but today the party is failing to provide “an appropriate and professional service” to its Jewish members and this is demonstrated in its “processes, behaviours and attitudes”, in unwitting prejudice, ignorance, thoughtlessness and racist stereotyping which disadvantage”, and in “the failure of the organisation openly and adequately to recognise and address its existence and causes by policy, example and leadership”.

Second, the report shows that once the antisemitism crisis is placed within four larger contexts, it is revealed as having much deeper roots and being much harder to eradicate than has been assumed.

The first context is historical. There is a long and evolving tradition of left antisemitism, little-understood, which these days often comes ‘dressed up as anti-Zionism’, which is even less understood.

The second is intellectual. Contemporary left antisemitism has a ‘philosophy’ of sorts. Large parts of the left are in thrall to the simplistic ‘two-camps’ world view that divides the world up into the good-oppressed and the bad-oppressors. That world view has turned the complex and tragic Israeli-Palestinian conflict into a cartoon or morality play peopled only by good and evil, to be romanticised and demonised.

The third is the unprecedented influence of the far-Left on the party today. The Corbyn surge has produced not only a mass membership but an experienced cadre of sectarians on the prowl, some inside the party, some stalking party members online, all of them spreading not only the polarizing and demonising two camps world view but also a trolling and bullying culture. It is simply a shaming fact that as Sean Matgamna has put it, for some Jews who resigned recently, the Corbyn surge plainly felt like an antisemitic purge.

The final context is one man. Around the neck of the party has been hung an albatross in the shape of Jeremy Corbyn’s political record (and that of some of his closest aides and supporters) of public support for antisemitic forms of ‘anti-Zionism’. In the absence of an auto-critique, we have had instead the defence of that record by party members. And that defence is how the normalization of antisemitism in the party is taking place.

I wrote the report mindful of two fears. Many Jews are understandably fearful that antisemitism could be normalised in the country too, if Labour gets into government. And then there is my tribe, still there in North Shields and places like it, fearful that there will never be a new economic direction for the country in which they can write themselves a future. I want a party that can address and allay both those fears. Maybe the report is my last go at persuading the Labour Party to be that party. If it can’t, we will need a new one that can.

Professor Alan Johnson is a senior research fellow at Bicom