CND is planning a national demonstration against Trident which will be the biggest ever protest since the Cold War height of the anti-nuclear campaign in the mid-80s.

The Campaign for Nuclear Disarmament revealed its plans during its conference this weekend. The organisation said the conference, which started yesterday and continues today, is the most important CND event since the Cold War. It has been focusing on how to win the fight to halt the replacement of Trident weapons systems based at Faslane on the Clyde.

CND says the anti-Trident march and rally planned for noon on February 20 next year in London is expected to attract "hundreds of thousands of protesters".

The anti-nuclear weapons campaigners say they have plans to organise an earlier emergency demo if Westminster holds the crunch vote on renewing the nuclear deterrent before Christmas.

It is thought in some quarters that the "main gate" vote could be brought forward in an attempt by the Tory government to exploit Labour Party divisions on the issue and prevent Trident becoming a defining one in the May Holyrood elections. The Scottish National Party would campaign against replacing the weapons of mass destruction.

However, the vote on proceeding with a like-for-like renewal is expected in the middle of 2016. Before the vote can take place the London government must complete the Strategic Defence and Security Review, looking at the threats facing the country for the years ahead.

That is expected soon after the Chancellor delivers his Autumn Statement on November 25. A vote on Trident could then theoretically take place before December 17, when the Commons rises for Christmas.

Ian Chamberlain of CND said: "CND are calling a Stop Trident national demonstration. This could be one of the largest mobilisations against nuclear weapons this country has seen since the 1980s.

"The idea is to have a massive demonstration before the parliamentary decision on replacing Trident, which some are hinting is going to be earlier than February, but we are still confident that it will happen after February. Our sense was that [an earlier date] was probably suggested as a way of undermining any opposition."

He added: "As an organisation we will be ready to call an emergency demonstration if the vote happens earlier."

While it has been many years since its Cold War heyday, the stirrings of a revival of CND have become apparent in recent months as the debate over replacing Trident begins to gather momentum across the UK.

There are now 35,000 paid-up members of CND. The growth in membership has gone from 30 per month to 200 a month since the campaign to have Jeremy Corbyn elected leader of the Labour Party began in June.

The growth rate has continued to increase since Corbyn, who is to become vice-president of CND, was elected Labour leader on September 12.

In the past week alone CND, which was launched in 1958, gained 100 new members.

While membership numbers are a fraction of CND's heyday in the mid-80s when membership reached as high as 100,000, its leaders are encouraged by recent increases.

Chamberlain added: "We’ve noticed an increase in interest since June because Jeremy raised Trident at practically every hustings event he did, alongside austerity. Those two issues were the central planks of his campaign."

The heyday of CND was helped in no small measure by one of the most famous anti-nuclear protests of all time when in 1981 a group of women set up a peace camp at Greenham Common base, where American cruise missiles were due to be sited.

Then, the cause was unilateral nuclear disarmament - the argument that getting rid of Britain's arsenal would lead to other nations following suit. Oppoents mocked such protests describing them as naive, while some even denigrated them as a tool of the Soviet Union.

Government papers released by the National Archives, show how senior Conservative ministers were worried that they were in danger of losing public opinion over the deployment of Cruise missiles.

However, when Labour took up the nuclear disarmament cause in its 1983 manifesto The New Hope For Britain, they were annihilated at the ballot box as Margaret Thatcher secured a second election victory. The manifesto was famously dubbed "the longest suicide note in history" by Gerald Kaufman, a member of then Labour leader Michael Foot's shadow cabinet.

However, the politicking did not prevent CND from holding its biggest ever protest against nuclear missiles in 1983, at the height of its powers, with an estimated million people taking part.

The protests were held to show opposition to the movement of Cruise and Pershing missiles to sites across Europe from the United States.

Next February's protest will focus on saying No to buying a new Trident nuclear deterrent system at a cost of up to £100 billion.

The UK's deterrent currently consists of four Vanguard-class submarines, each capable of carrying up to 16 Trident II D-5 ballistic nuclear missiles.

At least one submarine is constantly on patrol, while one undergoes maintenance and the other two carry out manoeuvres. The missiles are capable of hitting a target up to 7,500 miles away.

However, the Trident missile system, which was unveiled in the 1990s as a replacement for the predecessor, Polaris, is due to end its service from 2028. It takes about a decade to build and prepare a new submarine for service.

A vote in favour of replacing Trident would authorise ministers to negotiate the best deal for replacing the submarines from military manufacturers.