The Union flag and Saltire are seen flying side by side at Bankfoot in Perthshire ,Scotland
Scotland may vote to split up the United Kingdom but the 5.3 million English Scots may stop that happeningReuters

If you ask David Cameron what he thinks of the Scottish independence referendum, he'll tell you he wants the United Kingdom to remain intact but the decision is a matter for the Scottish people. Which isn't entirely true.

That's because around 8.5% of Scotland's 5.3 million population are English-born. And many are preparing to vote down independence in a bloodless anti-Bannockburn some 700 years on from Robert the Bruce's violent battle against London rule.

Polls have showed a narrowing of the gap between yes and no voters ahead of the referendum on 18 September. Two of the most recent from pollsters YouGov and TNS show a hair's breadth between yes and no voters. But in the latter, 19% of more than 2,000 respondents said they don't know how they'll vote.

So the 8.5%, a hushed English sleeper cell veiled in the foggy dew of Scotland's glens, could make all the difference in how the vote goes and if Alex Salmond, leader of the Scottish National Party (SNP) and a political Bruce for our times, wins his battle with Westminster.

"Independence is just to satisfy a minor number of Braveheart wanters," says Professor Lee Cronin, the Regius Chair of Chemistry at the University of Glasgow and a son of Ipswich, England.

"I do not think I would be able to stay in Scotland if it became independent," he adds, citing what the nation would lose - his £25m research group which includes 60 people, three spin-out companies and over 150 international collaborations.

"As soon as paralysis set in because of the negotiations that would occur, it would affect my research effort critically. I'm in my forties now. I don't have that many productive years left of thinking and running operational science, and to lose two or three years because the Scots are negotiating with the English seems a very dangerous state of affairs. And I'm not the only one thinking this."

Best of both worlds

It's difficult to get English-born Scots to admit they're voting against independence. Yet they're everywhere. Business people, military staff, students, the retired. Some don't want to risk alienating friends, others are concerned about the impact on their businesses. It's far easier for the pro-independence English to speak openly; a quick search on Twitter will spring up dozens of heartfelt, rousing and sometimes rambling posts.

Others may have been put off by a backlash against Harry Potter author JK Rowling, an English woman who has lived in Scotland for more than 20 years, after she said she would be voting against independence.

She was lashed by vitriolic tongues. A nasty section of the pro-independence movement called Rowling a "traitor" among other - and much worse - names. A few suggested she was being disloyal to Scotland after it supported her as a single mother before she made millions by writing the Harry Potter series.

Despite the general silence of English Scots who don't want independence, some don't mind raising the Union Jack and defending an arrangement that has lasted more than 300 years. In fact, some are even willing to hit the pavements and knock on doors.

Katie Dearden
Katie Dearden is a campaigner for Better TogetherKD

Katie Dearden was born and bred in West Yorkshire and is about to enter her third year of studying for an international relations degree at the University of Edinburgh. She "fell in love" with Scotland when visiting as a child and decided to study there. Now she hopes to stay.

Dearden is also a campaigner for Better Together, which is pushing for a no vote in the referendum. If it turns out to be a yes instead, she's not sure if she'll stay in Scotland and it's "something that I don't like to think about".

"I really do think Scotland has the best of both worlds with its own Scottish parliament and the backing of the UK. I think that's fantastic and I'm a massive fan of devolution," she told IBTimes UK.

"As a United Kingdom, we're great on the world stage. In the UN, the EU, G20, G6 - so many different organisations that we have a great impact with. And to jeopardise that in any way doesn't make sense.

"I can't see why, in this day and age, any country would want to separate and close itself from that. The world is ever increasing and growing and uniting together.

"It's an unnecessary risk, especially with the EU. It's not guaranteed that Scotland will be part of the EU. Automatically assuming that... Scotland would have a more important voice or maybe a better voice, as Alex Salmond sometimes implies, is a bit naive to me."

What independence means

The fundamental question of independence is clear. But the reality of what that independence will look like is as muddy as a peat bog. There are many questions left unanswered by the pro-independence campaign. These are vital questions, such as what would the currency be? What would the business and financial regulation systems look like? Would Scotland join the European Union? Will it be an open border?

Salmond and his team have been criticised for not spelling out in detail what form of independence people are voting for and for making promises – such as that they will join the EU and keep sterling – that they cannot definitely keep. The vagueness has been seized upon by Better Together, who is urging Scotland to vote for the certainty of the UK over the uncertainty of going it alone.

Some of these questions will trouble the English in particular, who may have family below Hadrian's Wall, or who own firms working either side of it. There is the potential for another labyrinthine layer of state bureaucracy between their blood and businesses. Regulation, border controls, taxes – or maybe none at all. But why take the risk of barrier-building by voting for independence?

"The argument [for independence] is not logically consistent," says Cronin, who emphasised that he's speaking as an individual and not on behalf of the University of Glasgow, which has kept a neutral stance.

Scottish Independence
Scottish National Party's Alex Salmond wants to retain the poundReuters

He argued that retaining the pound, as Salmond wants, necessitates giving away sovereignty to the Bank of England and so, by proxy, Westminster. And there is no legal precedent that means Scotland would be guaranteed to keep it. This may lead to a new currency for Scotland and, in all likelihood, much higher borrowing costs for its government.

Moreover, Cronin says he is "not just a UK unionist, I'm a unionist in general".

"I think the European Union is a very good thing and it doesn't make any sense to split one union and say 'we're pro-Europe'. Well if they're pro-Europe then for the very same reasons they must be pro-UK," he said.

And Cronin is also concerned about what independence means for academia. Much of his research funding as a scientist comes from the UK and EU. He says it's not been made clear to him how independence would affect his academic funding.

More broadly, he thinks it will have a negative effect on scientific research in Scotland's world-leading universities. There would be a smaller pool of funding and less competition for it in a diminished system.

"It's like playing sport. If you don't have any other people to compete against then you're not going to get any better," he said.

Political barrier

Lincolnshire-born Daniel Swain is a member of the Labour party and an economics graduate from the University of Edinburgh, where he wrote a dissertation on the effects of the size of a nation's market on its exports. He looked at Scotch whisky as a case study.

"A lot of the nationalist arguments based around trade and economics are that if the Scottish government was independent it would be able to market Scotland's goods better and Scotland would be able to export more," said Swain, who will vote no in the referendum.

"But actually, the Scottish government already does that – probably better than most national governments are able to because it has the benefits of the UK trade office as well.

"And then also the key in determining the export of industries is the size of the national market. So Scottish export markets, including Scotch whisky, benefit from having a big national market as opposed to a small one."

Swain is unconvinced by the economic case for independence, which relies in large part on the North Sea oil and gas fields, where production is forecast to fall sharply over the coming decades.

He thinks Scotland must retain its influence on Westminster politics by being able to send MPs down to London, a global centre of capital, trade and commerce where big economic decisions are made.

"If Scotland put up a political barrier, it's not going to be beneficial to the people of Scotland because I think they're going to need to be able to affect decisions at that level," he said.

Lee Cronin
Lee Cronin isn't sure he could stay in Scotland if it became independentUniversity of Glasgow

Pro-independence campaigners say an independent Scotland could make itself more competitive. It could make its own taxation regime, they say, develop new industries, create a sovereign wealth fund from North Sea revenues – carve out a new model economy.

But Cronin fears more bureaucracy and less competitiveness would be the consequence of independence.

"Basically we're going to have another administration layer added on, which is great for the politicians who want power. But I don't want them to have power," he said.

"I want power. I want power as a voter to basically get on with things. I demand better value for my money.

"I demand to see Scotland stop using the wrangles with the English for incompetence and to start using their incredible abilities – the prospects, the tourism sector, the education sector – to build and advance and compete. We're not doing that and it's a sorry state of affairs.

"This has always been my problem with Scotland. I've been here for well over 12 years. I don't see who is making any money. There seems to be an ever-decreasing number of people making things, manufacturing things, coming up with ideas, and a massive, massive taxpayer-funded set of administrators generating more nonsense for me to deal with. And that is a really, really dangerous set of affairs.

"I want the Scottish economy to be more agile, to be more responsive and to use devolution to do that. But they haven't. They've used it to create a set of administrative fiefdoms that serve themselves. And when the administrators serve themselves, very little gets done."

Anglophobia

It's not a significant problem, but anti-English sentiment exists in Scotland and as the independence debate fires up, sparks of prejudice fly out.

In the run-up to the referendum, the number of white English people reporting racist incidents against them to Scottish police jumped by 80% to 146 in 2012/13. This accounted for 5% of all reported racist incidents in Scotland over the year.

Swain said he's had people say things to him because he's English.

"I remember one old man saying he was voting 'yes' to get rid of all the English people. It's not a particularly prominent problem, but you get it now and again," he said. "A lot of people when they're asked will say: 'I'm not anti-English, I'm anti-English government.' I'm not sure how sincere that is."

Dearden, on the other hand, said she's had a decent experience when hitting the streets to campaign against independence.

"Most of the time it's been really positive. I have heard that some people don't get as good an experience occasionally," she said.

"But the people I've spoken to aren't anti-English, they're just quite disillusioned with politics and they're looking for a way out. In no way have there been any aggressive, divisive comments about English people. It's just been positive really."

Cronin described the Scottish as "very open-minded" and said it is a "very friendly country".

"I've had banter with people and I know there are people who feel passionately about what Margaret Thatcher did to Scotland and all this, that and the other. And I think they misunderstand what actually occurred and how politics works," he said.

"There is a slight parochialism that is here but I haven't experienced any negativity on my part."

Identity question?

Some attack any focus on national identity in the independence referendum debate. In fact, they reject entirely that the debate is at all about identity. To them it is about economics and political control, a move away from Tory domination and towards self-governance by the people living in Scotland.

So even asking the question of how the English-born will vote is to misread what is happening on the ground. This is no Braveheart cliché or tartan revolution. It's about the localisation of political power and decision-making.

Braveheart
Mel Gibson as William Wallace in the film Braveheart.Creative Commons

But the very idea of splitting from the UK seems to be centred on nationhood; that going it alone allows Scotland the chance to create its own financial and economic values, principles and rules defined by the unique political culture in Scotland.

They see it as a move towards communitarian, socially conscious politics, the antithesis of the perception of Westminster as a hive of market-loving neo-liberal individualism. Then again, this is hardly unique to Scotland.

"The same aspirations for reform are held up and down the UK, there's nothing unique about the views of yes voters in Scotland, we're just lucky enough to have been handed a shot at political reform on a plate, and realise that the chance may not come again in our lifetimes," said one Reddit user discussing the issue.

"If there was a perception that UK politics was capable of genuine, significant reform, I've no doubt that many yes voters, me included, would be voting no.

"When you talk of 'defining Scottish society differently', I'd argue that most would rather achieve these same objectives within the framework of the UK, than out with it. We just don't believe that staying in the UK offers, or will ever offer, that opportunity."

Cameron's legacy

It wouldn't be the first time the English have done it to themselves over Scotland. When Edward II lost at Bannockburn, he had only managed to muster half of the army he wanted. Some of his best English knights hadn't turned up to fight alongside their king in what was a humiliating defeat for him.

From students, to military personnel, to business people, and more – there are hundreds of thousands of English Scots living and voting above the border.

It would be just as painful for Cameron if a hallmark of his prime ministership was the secession of Scotland. But if most of the army of English voters living in Scotland turn up, it will probably be enough to help him deliver a fatal blow to Salmond's battle for independence.