Latest News About England: Scottish independence: English invasion faces defiance in Granite City

As David Cameron and his cabinet arrive in Aberdeen, Alex Salmond is rallying his SNP party for a major battle to win hearts and minds

In Aberdeen on a cold Friday afternoon, they are weighing up the idea of divorce. It is now just over six months until Scots have to make their decision on independence. Opinion is split among shoppers trudging through the city's windswept streets. Some can't wait to cut loose and be free after 307 years.

Shop worker Marian Forbes, leaning into a stiff breeze on Union Street , abhors the "condescension of the English". She even viewed David Bowie's intervention in the independence debate last week, when the singer called on Scots to "stay with us", as part of a Westminster plot.

"The problem is that since the battle of Culloden the English think they own us," she said. "They'll do anything, use all sorts of dirty tricks, to keep us under their thumb. Cameron is putting a lot of us off with his moves."

But Bill Kelman, a 65-year-old approaching retirement, takes the opposite view. After Gordon Brown's warning last week that Kelman's pension would be affected by independence, his mind is made up: "I'm totally on for staying in the UK. I can't even contemplate, never mind risk, losing my state pension."

In the Granite City, which is dependent on oil, more seem in favour of staying together than going it alone. In the gloom of Aitches ale house, a favourite watering hole for oilmen coming ashore after working on the North Sea rigs, the barman spoke for well-paid customers who want things to stay the way they are: " It's all no in here, mate. It better be anyway."

On Monday Aberdeen will find itself centre stage in the independence debate when David Cameron leads his entire cabinet to this corner of Scotland to symbolise his government's commitment to the union. He will pledge to back investment in North Sea oil and gas and suggest that if Scotland leaves the UK the industries that provide so many jobs might not be so strong. Not wishing to be outdone, Alex Salmond will stage an SNP gathering not far away, arguing the precise opposite.

Scots await Cameron and his cabinet with mixed feelings. Glaswegian financial adviser Omar Choudry, 30, in Aberdeen visiting friends, said: "He's got guts coming up here, I'll give him that. Most of my peer group are pro-UK, with fears over the EU being the biggest point and the currency issue is a clincher. If it's not broke, don't fix it."

However, haulier Andy Tennant, 42, said that the Conservatives' warnings had already antagonised people like him so much that they had switched to Salmond. "It's just got my back up. We need a proper debate. If they [Westminster]want to try to scare or bully us, then that is a massive turnoff, not just for me I bet."

For the past fortnight Scots have heard little but dark warnings from Westminster – and Brussels – about the cost of a yes vote on 18 September. Tentative signs that the yes campaign might just be closing the gap on the no team in opinion polls stirred the pro-union forces into action.

First came publication of a letter from Sir Nicholas Macpherson, permanent secretary to the Treasury, to the chancellor, George Osborne, on 11 February. The top mandarin spelt out why a currency union between an independent Scotland and what would be left of the UK would be, in his words, "fraught with difficulty".

His arguments were many and colourfully put for a civil servant: "The Scottish government is still leaving the option open of moving to a different currency option in the longer term. Successful currency unions are based on the near universal belief that they are irreversible. Imagine what would have happened to Greece two years ago if they had said they were contemplating reverting to the drachma."

Two days later, Osborne said Scotland would not be able to carry on using sterling if it became independent. He used an analogy designed to bring the reality home: "The pound isn't an asset to be divided up between two countries after a breakup like a CD collection." Labour and the Liberal Democrats quickly rallied behind the Tory chancellor.

Salmond accused the Westminster parties of a combination of bullying and bluff. But then came an arguably even more dramatic warning to those flirting with independence; one from the heart of the EU. European commission president José Manuel Barroso went on television to say it would be "difficult, if not impossible" for an independent Scotland to stay inside the European Union.

The SNP's official position is that Scotland will be able with no great difficulty to negotiate the terms of its future independent membership of the EU before what it hopes will be Independence Day 24 March 2016, becoming its 29th member state. Then the unionists thought they had scored a populist hit when last Wednesday Bowie sent a message via Kate Moss that he wanted Scotland to "stay with us" in the UK as she accepted on his behalf an award as the best British solo artist at the Brit awards.

All bad news for the yes campaign? It certainly had the feel of a concerted push, designed to instil fear. But the SNP knows how to fight and found experts with very different views on the currency and EU membership. Former director general of the European commission Jim Currie told members of the Scottish parliament that Barroso was plain wrong: "I don't think he was correct, and I don't necessarily think that opinion is shared either among all the member states or even necessarily within the commission."

Salmond predicted that scare stories from London and Brussels would backfire and there was some suggestion he was right when a new poll moved further in the SNP's favour. The gap between the yes and no camps was down to nine points, with yes on 38%, against 47% for the no, according to a Survation survey. The gap had been 20 when Survation asked the question last month.

The SNP thinks the polls are moving in its favour, but the unionists believe that on the substantive issues they are on a roll. Scottish lawyers and constitutional experts who have been summoned before committees of the Commons and Lords in Westminster are warning of wider, long-drawn-out uncertainty and constitutional quagmires – including over whether Scotland will be able to negotiate membership of the EU in time for Salmond's Independence Day – in the event of a yes. They warn of nightmarish arguments over oil and the future of shipyards that will drag on for years. Adam Tomkins, the John Millar chair of public law at the University of Glasgow, told the Commons Scottish Affairs Committee recently that the idea that a 307-year-old union can be unpicked so fast – between September this year and March 2016 – is "risible", "preposterous" and "ludicrous". Unionists say the argument cannot really begin in earnest until after the 2015 Westminster elections, leaving impossibly little time.

Secretary of state for Scotland Alistair Carmichael told the Observer: "The SNP's claim is that it will negotiate its way into the EU on the same terms as the UK within 18 months. This is not feasible, especially in the context of seeing how long it has taken other countries joining from outside, such as Croatia or Cyprus, which both took over a decade. No one has done it in less than two years. The timescale on the EU alone is beyond optimistic."

As the cabinet heads north, the predominant view in Aberdeen seems one of caution amid the competing claims. The city's paper, the Press and Journal, called for people to be wary of leaping into the unknown before they had seen the details. "People are naturally wary of fundamental change and it goes against the grain to sign up for anything until they have read the small print," it said.And a majority of younger Scots seemed pro-union. James Davidson, 21, studying media, said the prospect of Scotland losing its currency was too damaging to contemplate: "I don't want Alex Salmond to be sole in charge. I don't like David Cameron, but it's nice having the security of the UK." Hardly a ringing endorsement for the view from Westminster but, perhaps, a small sign that some of the uncompromising messages being sent north may be filtering through.