ONE of Labour’s greatest achievements since Jeremy Corbyn was elected leader in 2015 has been to open up new space for political debate.

Years of Establishment consensus hollowed out our democracy.

When Margaret Thatcher said her greatest achievement was Tony Blair, she was not merely referring to a shift in the “centre ground” away from social democracy and towards unrestricted neoliberal capitalism.

Her observation was that Labour, as the political expression of organised labour, had given up. After years of attacks on working-class communities and the public sector under the mantra “there is no alternative,” she had come close to making that lie a reality.

Tory rhetoric makes much of the language of freedom: “liberalising” services, “deregulating” industries, cutting “red tape.”

The neoliberal reality doesn’t match the hype. For one thing, there was no “deregulation” of Britain’s draconian anti-trade union laws, the most restrictive in the developed world.

Deregulation has disempowered the public by removing leverage over the actions of business, all while new forms of super-regulation, in the forms of international TTIP-style trade treaties and the “capitalist constitution” formed by the EU’s Maastricht and Lisbon treaties, have encroached on our democratic space, reducing the options available to elected politicians.

By breaking with the free market fundamentalism that has dominated British politics for four decades, Corbyn and his team have widened our horizons.

The challenge to Establishment interests Labour represents now that it is committed to expanding public ownership, redistributing wealth and strategic management of the economy in the interests of the public has provoked a ferocious reaction in the form of unrelenting misrepresentation of Corbyn, endless smears and wall-to-wall attacks in the press on the flimsiest grounds (while the Conservatives are almost never called to account for genuinely scandalous conduct).

One form of attack is to make constant demands of the Labour leadership that it disown allies or principles. Corbyn has been called upon at various points to denounce the Stop the War Coalition, the Morning Star and Momentum; critics have also demanded he abandon previous criticisms of Nato, the European Union or nuclear weapons.

This is why John McDonnell deserves congratulation for addressing the Marx 200 conference organised by the Marx Memorial Library at the weekend.

As he noted, the Establishment aims at creating a “climate of fear” in which socialists self-censor in order to appear “politically correct.”

The aim is to systematically shrink those new spaces Labour has opened up. To blunt Labour’s radicalism and force it to swear allegiance to the old gods.

Marx, as McDonnell pointed out, was an acute observer of capitalism and he has a huge amount to teach us about the crisis-ridden capitalism of today and, crucially, what we ought to do about it.

That our shadow chancellor can discuss Marxism and its potential for helping us change the world is a shot in the arm for our democracy.

It has caused a predictable meltdown at the Daily Mail, where a bizarre attack piece was forced to dredge up former Simply Red singer Mick Hucknall to denounce McDonnell for attending the event.

But there is no sense in retreat under fire. Corbyn and McDonnell’s critics want a Labour Party that embraces capitalism, imperialism and war. Concessions will not satisfy them but simply embolden further attacks.

The left must stick to its guns: fighting for our right to debate issues that affect working people without being drummed out for heresy or bullied off platforms.

And it must take the fight to the enemy, pushing for a fuller debate over areas where Labour policy still leaves much to be desired — such as our Nato membership or our nuclear arsenal — as well as over the democratisation of the party itself.