In conspiratorial politics, it’s not what you think but how you think that matters. And for four years, the Labour Party gave licence to supporters to think in the paranoid style.

Left-wing populism died as a political project in Labour’s crushing electoral defeat in 2019, but that does not mean it is dead in the minds of a portion of its old supporters. They still mirror the populists of the right. Instead of thinking that an elite class of experts cows “the people”, they think that an elite class of super-rich neo-liberals rigs the system. Instead of wanting to throw off the yoke of the EU, they want to end “Zionist” control of British foreign policy.

The 21st Century version of the “socialism of fools” may have left Labour’s shadow cabinet, but it has not left the left. Why should it? Millions voted for it, after all.

The past will not let Labour go because antisemitism is a self-correcting mechanism that can explain every eventuality.

If you argue against it, you are part of a Jewish plot to cover up the crimes of Israel by besmirching socialists “without a racist bone in their bodies”.

When Keir Starmer attempts his timid version of de-Stalinisation and tries to move on, he must surely be the plaything of Zionist cabals.

George Galloway is running in the Batley and Spen by-election, selling himself to Muslim and white left voters as the pro-Palestine candidate. Starmer is a “Zionist,” Galloway declared as he announced his candidacy, and the way to destroy the pro-Israel interloper is to vote Galloway and stop Labour retaining the seat.

If you live in the world of substance rather than style, the idea that Labour has an anti-Palestinian policy makes no sense. Starmer made Lisa Nandy – a former chair of the Labour Friends of Palestine – his shadow foreign secretary. In a attempt to hang on to Muslim voters, Labour canvassers are now telling them that it is party policy to support a viable Palestinian state and oppose illegal settlements on the West Bank. Labour condemns the recent violence in Israel and Gaza as “horrific,” its election leaflets say, while tactfully avoiding mention of the gifts that Hamas and its rockets brought to the party.

For good measure, Labour adds, “the strongest voices in politics on Kashmir are Labour voices” and points to the Conservative Party’s links to India’s ruling Hindu nationalists.

How can Galloway, or thousands of click activists, maintain that Labour has become a tool of the Israeli state when the facts show the party’s formal foreign policy positions have not changed since the Corbyn era?

As soon as you move from what Labour thinks to how it thinks, you understand. Starmer and Nandy are not sinister politicians.

They understand anti-Jewish hatred, and they would not inflame it.

I could never imagine them standing by while racists and half-mad fantasists drove Jewish MPs from the Labour party. They would not defend Hitlerian murals or honour men who murdered and castrated Israeli athletes.

Populist leaders succeed not just by inciting their supporters but by giving them permission to indulge prejudices they once kept hidden, or never knew they had. Their supporters enjoy the liberation and do not willingly return to the old restraints when party leaderships and party lines change.

Because he wants to and because he has to, Starmer takes a hard line against anti-Jewish racism.

But every time he does, he increases the anger against him on the left and among those Muslim voters for whom Palestine is an overriding issue.

Every time he attempts to pacify that anger, he revives memories of the sectarian hatred he wants to suppress and revives fears of antisemitism. There is no easy way out.

Suppose Labour shuns organisations that advocate boycotting Israeli goods. All antisemites want to boycott Israel but not everyone who wants to boycott Israel is an antisemite. How does Labour distinguish? And even when it has, how does it protect itself from the accusation from the left that it is the tool of Zionist puppetmasters, because the last leader of the Labour party would have happily honoured men Starmer now shuns?

Galloway would never have stood against Labour if Jeremy Corbyn was still in charge. The pair have acknowledged their kinship. Galloway openly supported Saddam Hussein and Bashir Assad. Corbyn was paid by Iran and doubted Putin’s responsibility for the Salisbury poisonings. Corbyn congratulated Galloway on his “astonishing” victory when he defeated Labour in the Bradford West by-election of 2012. Galloway once said, “I support all of Jeremy Corbyn’s policies. I might put them a little differently. If you don’t mind me saying so, I might put them a little better.”

Only two years ago, he would have been the candidate that most closely represented the leader of the Labour Party’s views.

Now the new leader must fight him and fight the permission for paranoid politics his predecessor gave.

As the post-Trump Republicans are showing in the US, populism doesn’t die when populist leaders fall.

Once moral standards have gone, it is the work of a generation to put them back in place.