THIS weekend’s CND conference is its most significant since the end of the cold war.

This is a big claim but I do not feel that it is an exaggeration. I can see great possibilities for change over nuclear weapons — because we are facing a unique combination of events.

First of all we are at a once in a generation decision point.

The last time we had the opportunity to protest against — and potentially prevent — the building of a new nuclear weapons system was in the early 1980s.

Thatcher decided to build the first Trident submarines at the same time as she agreed to the US putting cruise missiles in Britain.

Next year Parliament is set to vote on whether or not Thatcher’s Trident system is replaced, the so-called Main Gate decision on whether to start cutting the metal on the new subs.

This vote was promised in 2007 by the Labour government as it pushed the first Trident replacement vote through Parliament for the concept and design phase for new subs.

This second bite of the cherry was reportedly necessary to make many Labour backbenchers vote for Trident.

Even with that promise, there was still a huge backbench rebellion.

But ministers are happy to bandy around assertions that they will replace Trident anyway. And they may try to push it through before Christmas, according to kite-flying articles in last weekend’s press.

Of course that decision point has been long expected.

The totally unexpected and potentially transformatory factor in the mix is the election of Jeremy Corbyn as new leader of the Labour Party.

As is well known, he is a lifelong CND member, is opposed to Trident and is taking the Labour Party into a debate, the outcome of which is likely to be an anti-Trident position.

Even if there are insufficient numbers to defeat a government motion, this would end the cross-party consensus which the Prime Minister may deem necessary to push Trident through.

Corbyn has said that if party policy changes, once in government Trident replacement will be cancelled.

But Trident has already been a significant political factor in British politics for the last couple of years because Scotland, which hosts Trident submarines and weapons at Faslane and Coulport, is opposed in its significant majority to Trident.

The Scottish government is opposed to Trident and virtually all Scottish MPs in Westminster are opposed to Trident.

A Westminster vote to impose Trident replacement on Scotland will absolutely lack legitimacy. Such a vote is likely to trigger a second independence referendum. And there is nowhere for it to go elsewhere in the UK.

During the coalition government years, the Lib Dems actually made some attempts to shift Britain’s nuclear posture, away from four subs on continuous armed at sea patrol to fewer subs only out on armed patrol in times of danger.

What they think now matters less, but their conference recently agreed that they would vote against Trident replacement in Parliament.

They are not exactly sure what they want instead of full-scale replacement. But although they are now small they should not be written off in the Trident debate. They are down but not out.

Of huge importance is the fact that for many years there has been a consistent majority — shown by the polls but denied by pro-Tridenters — against Trident, across civil society and from all walks of life and political persuasion.

From military figures who think its opportunity cost (the alternatives you lose if you plump for it) is too high for conventional weapons, from Major General Patrick Cordingley to the Tory chair of the defence select committee Crispin Blunt MP.

Of course there are trade unions, anti-austerity campaigns and faith communities, and the anti-Trident, anti-austerity bloc that featured strongly in the general election, even if it didn’t translate in all case into seats: the Green Party, SNP and Plaid Cymru, as well as the SDLP from Northern Ireland that is firmly against.

And, completely unreported here in Britain, there is an enormous movement of over 100 states globally — yes states, not movements — demanding that a global ban treaty is introduced to outlaw nuclear weapons.

So that adds up to a pretty powerful case for the significance of this moment in the life of the anti-nuclear movement.

We have a genuine opportunity to win the struggle against the quite extraordinarily anachronistic approach of the government: insisting that nuclear weapons are necessary for our security when quite clearly they don’t meet contemporary challenges like terrorism, climate change, pandemics and cyber warfare.

The illogic of “deterrence” seems more bizarre than ever: we have nuclear weapons in order not to use them? What absurdity to rest Britain’s national security and the future of the planet on a game of bluff.

Come and join us for the first public debate on this issue since Corbyn was elected leader of the Labour Party. Times are changing.

• Kate Hudson is general secretary of the Campaign for Nuclear Disarmament. Scrapping Trident: Strategising for Success in 2016 takes place tomorrow — Sunday October 18 at the Arlington Conference Centre. Find out more at www.cnduk.org