THEY had a better class of protester in the 1960s.

After the American nuclear depot ship Proteus arrived in the Holy Loch in March 1961, one bunch of resolute marchers appeared on the streets of Glasgow with a splendid slogan on their banner. "Killers Withdraw!" it demanded. Sadly, the US Navy declined the invitation.

Douce Dunoon, meanwhile, had witnessed a rally that managed to be both furious and quaintly hospitable. While rowdies harassed American sailors, another set of demonstrators waved posters with the apologetic message "Americans – we like you, but not Polaris". Those present were brought to order by a clergyman named Kenyon Wright. Some things never change.

Or, rather, things change imperceptibly. When Christians, Communists, Nationalists, Labour people and trades unionists were marching to rid Scotland of weapons of mass destruction at the start of the 1960s, unilateral disarmament was supported by just 20% of the population. By the time the Faslane peace camp was established in 1982, even a young Tony Blair thought it wise to join the Campaign for Nuclear Disarmament (CND).

When Trident was deployed that year, few parts of the realm known as civic Scotland were absent from the argument. The STUC, Cosla, churches, Labour, SNP and more besides were united in opposing the latest in lethal weapons systems. They had reached much the same conclusions as their predecessors 20 years before, for much the same reasons.

In international terms, this weapon of mass destruction was as illegal as it was immoral, as futile as it was fearsome. It was a hideous waste of public money that served only to make central Scotland (and more besides) a first-strike Soviet target. It could never be used by any sane government and it was an affront to democracy. By 1982, opinion was settled: Scots didn't want it.

That hasn't changed. True, in May this year there was an attempt by Lord Ashcroft, multimillionaire Tory backer and patron of opinion polls, to spin one of his surveys towards the conclusion that "most Scots" support Trident renewal. The peer allowed himself two shots at the question and found that either 51% or 53% wanted some version of the weapons system. However, all was not quite as it seemed.

The exercise was meant to rebut a Scottish CND poll showing that 60% are against "the UK Government buying a new nuclear weapons system to replace Trident", with only 14% in favour. Unfortunately for Ashcroft, he forgot to quit while he was ahead. When his pollsters asked, "In principle, do you support or oppose the UK having nuclear weapons", only 37% of Scots could be found in support against 48% opposed, with 15% undecided.

Then the Ashcroft survey posed a question that has turned out to be oddly prescient. Question six on his list was this: "Imagine Scotland became an independent country after the 2014 referendum, but the rest of the UK wished to continue leasing the Faslane naval base. In these circumstances, do you think the UK's nuclear weapons submarines should or should not continue to be based in Scotland?"

"Continue leasing" was perhaps not exactly what Ashcroft meant to say. Still, only 35% said the nuclear boats could stay in such a circumstance while 50% said they should find a new home. Once again, 15% were marked as "don't know". The attempt to prove that majority opinion has altered after decades of consistent polling looked a little flimsy.

Ashcroft's effort was evidence, nevertheless, of a change since the 1980s. Back then, few took seriously the possibility that Scotland could be contemplating independence in the second decade of the 21st century. Few imagined, meanwhile, that Labour, north and south, would have purged themselves of unilateralism. The idea that a London government might have to secure its right to use Faslane and Coulport was unthinkable.

Scots have been living with nuclear weapons for a very long time. The fact has given us a perspective that is not instantly available to people in the south. As the historian Richard Finlay put it in his 2004 book Modern Scotland 1914-2000: "It is worth pointing out that the campaign against weapons of mass destruction now has the longest pedigree of any single issue in Scottish politics, and the siting of nuclear weapons in Scotland has provided a rallying point for probably the most socially diverse of all protest movements."

Patently, there are plenty of people in England, Wales and Northern Ireland with a rational horror of the things cooked up in the name of "defence". The long campaign of the Greenham women is an obvious example. But in these parts we have grown up, most of us, with those sleek, black creatures prowling the Clyde without let or democratic hindrance. If we allow ourselves to pause, we become intimate with dread, familiar with disgust. The shadow never lifts.

Why would opinion alter, then, in the face of a Coalition review of nuclear "options"? Whether you accept Ashcroft's £20-25 billion Trident "replacement cost" estimate, or prefer the £100bn price tag for the life of the system suggested by the SNP, CND and others, vast sums are at stake. They are to be risked, moreover, in a period of withering austerity when no plausible excuse for the weapons' use can be identified.

The billions are to be spent, whether on a like-for-like replacement or a slightly cheaper system, while soldiers are being made redundant and wages are falling. For all the talk of economies, the nuclear fleet remains the biggest single item of British defence expenditure and each of the Westminster parties nowadays regards it as inviolable. The fly in their ointment is a referendum to be held in Scotland in 2014.

Last week, The Guardian carried an editorial that saw nothing odd about describing Faslane as "relatively remote". Readers in Glasgow, barely two dozen miles from the warheads, were entitled to wonder about mental landscapes. But the truth is that the sort of thinking applied to Scotland and nuclear weapons has altered little since the 1960s. The Clyde suits the Ministry of Defence and it has no intention of quitting.

That could become a problem. The SNP continue to insist that if they become the government of an independent Scotland the Trident boats will be removed. Last week, Nicola Sturgeon told the BBC: "Politicians, often and sometimes justifiably, get criticised for a lack of principle. Getting rid of Trident is an issue of principle, certainly for the party and government that I represent. It's not a bargaining chip."

Sturgeon was responding to a tale that had inspired The Guardian's blithe editorial. Enthused by David Cameron's demand for stories to scare the Scots – or to advertise the benefits of Union, if you prefer – someone at the MoD had got carried away. In a curious echo of Ashcroft's question, they had briefed a political correspondent to the effect that Faslane/Coulport could be declared "sovereign UK territory" in the event of independence.

"Sources" made it clear to The Guardian journalist that the Scots would be given little choice. If the jewel in the MoD crown was not handed over, London would drive a punishing bargain in independence negotiations. In effect, a slice of Argyll and Bute would be annexed. In the small hours, as The Guardian's website erupted with accusations of colonialism, imperialism (and some SNP delight), the Downing Street press office was roused.

At 1.44 am, a functionary took to Twitter to state: "This govt has not commissioned contingency plans over Faslane. No such ideas have come to SoS [secretary of state] or PM. They would not support them if they did." By the next morning, a spokesman was at pains to say that the scheme was neither "credible nor sensible". True enough, but the statement failed to answer a couple of questions.

First, what on earth could have inspired the MoD to come up with such a notion oblivious to the likely reaction? At no point was it suggested that The Guardian's report was inaccurate in itself. Secondly, just what does the MoD propose to do if, by chance, the Scots vote for independence? The insight given into Whitehall thinking was hardly likely to still the demand. To proceed as though a No vote remains a certainty is, at best, dishonest.

The abiding fact about anti-nuclear opinion in Scotland is that it has long outweighed backing for independence. Before last week more people supported the removal of Trident than were prepared to vote Yes. The effortless arrogance of the MoD, with or without Downing Street's sanction, must have persuaded many that the best way to achieve one ambition is through support for the other. At a stroke, those "sources" made independence more likely.

For now, two issues are agreed. First, it would cost many billions to remove the nuclear boats and provide new facilities elsewhere. Secondly, the MoD has failed to identify an English or Welsh port capable of matching the benefits offered by the "remote" Clyde. The Commons Scottish Affairs Committee has heard that the nuclear boats and their weapons could be removed from Scotland in two years, but that a replacement facility could take 20 years to construct.

Barrow-in-Furness lacks a big enough dock and its approaches would require "significant dredging". Milford Haven has deep enough water, but also a huge liquid natural gas facility, one that could do without naval accidents. Devonport lacks the space to duplicate Coulport, its warhead store and its floating dock. Falmouth, handy for Devonport, was rejected in the 1960s because it has "a strong tourist economy". Two villages would have to be levelled and a lot of people would have to move.

Just as half a century ago, nowhere in England or Wales is deemed quite "remote" enough to justify the honour of hosting Britain's deterrent. Equally, there is the fascinating opinion offered in March to the Bloomberg News service by Hew Strachan, professor of the history of war at Oxford. Since he is also a "strategic adviser" to the armed forces, his view is worth considering.

"There has been a fear in London of even discussing Scotland and related military issues," said the professor, "because of the Pandora's Box complex. There is concern in the Ministry of Defence that public opinion could stop Trident being relocated south of the Border." Who, in honesty, could blame the people of England for that?

Instead, some genius decides to do the SNP a favour by suggesting that a Union flag could be planted on Argyll and Bute. Rather than upset English voters, the Scots and their democratic will could be held in contempt yet again. Downing Street might deny any such intention, but it has failed to offer alternatives. Defence Secretary Philip Hammond, meanwhile, has told the Defence Select Committee that it would take 10 years, not two, to remove Trident. He added, casually, that Scotland would have to meet part of the cost of shifting the weapons Scots never wanted.

In March, a meeting of MPs in Westminster Hall heard from Ian Davidson, the Labour MP for Glasgow South West who chairs the Scottish Affairs Committee. He, for one, was already sceptical of the idea that there could be "a United Kingdom base in a separate Scotland". Such an installation would have to be secure, and certain Scottish waters would have to become UK sovereign territory. But as Davidson also said: "There could be an interesting situation if the Scottish Government instructed Strathclyde police to beat back protesters from outside a UK-owned and maintained Faslane base."

So take Downing Street at its word. There is no annexation plot and no contingency planning. Instead, they mean just to sit tight if independence is our choice. Meanwhile, bizarrely, the SNP intend to take a non-nuclear Scotland into Nato's first-strike nuclear alliance. The bad old dream is far from over. What's clear is that a vote for the Union will render it permanent.