Can independence be lost or found in the search for our sense of belonging?

"I am a Scottish patriot," the Estonian academic announces as she stands in the rain on Glasgow University's lion and unicorn staircase, its old, old stones tinged green by damp. "I even like the climate."

Lea has been in Scotland eight years. Her work is here; her life is here: so, too, is her vote.

"I'm a Yes," she explains. "Scotland would make such a nice independent country. I have always felt an affinity with small nations, places where people can decide their own destiny."

The referendum, after all, is deja vu for Lea. Today's rows and warnings take her back to Estonia in the 1980s, during the death throes of the Soviet Union. She has, she says, felt what she sees as the hope and empowerment of one side and fear of the other.

"I organised a Popular Front group in my school," Lea says, remembering herself as a pro-independence activist a quarter of a century ago. "Teachers urged me not to. They said it wasn't safe, that things could change, but I did. We were young and we were optimistic: we would have eaten potato peels to be free; we would have suffered any hardship.

"But some people were scared. Multiple foreign experts were summoned, each proclaiming such a small country as Estonia - barely a million people - would never survive as a separate independent state.

"They wrote long reports about how life in Estonia would become worse, and that the end result would be a catastrophe. But Estonians took a leap of faith. Since then we have done exceptionally well.

"I can easily imagine a similar future for Scotland. One where people feel a part of the state and the government truly represents them, rather than one where they are far removed from their statesmen."

This is a big theme for Lea. She doesn't like the tone from Westminster, from faraway politicians. It puts her back up, even as she speaks. "They have this certain superior and arrogant way of looking down on Scotland," she says, raising her shoulders and shuddering. "They speak as if Scotland was a smaller, stupider brother of England."

Do her Estonian friends in Scotland feel the same? Yes, she says, mostly. "They have the same background."

The same experience, she might have said, of seeing their nation become a state. Balts, of course, however enthusiastic for independence, won't swing the referendum.

However, collectively "New Scots", 460,000 of them born in England, just might, provided the vote is close enough. And that is something nobody seems to want to talk about.

It is the great referendum taboo.

The Yes campaign - mindful of its "welcoming" pitch on immigration and the electoral dangers of appearing anti-English - flinches at words like "foreign".

Better Together is a little more comfortable with the concept of "foreignness". It uses the "F" word to describe the rest of the UK after independence. But it's stayed clear of talk of an ethnic split in support for independence.

The role of incomers, campaigners are painfully aware, has played big in other independence processes. Take Lea's Estonia. A quarter of its population is Russophone. This complicated things in 1991 and it complicates politics now.

Or Quebec. Its sovereigntists lost both their referendums - the only independence plebiscites ever to fail. The second, in 1995, was close, within a whisper. Part of the "Oui" camp's post-mortem was a brutal claim that allophone immigrants had helped "Non". Jacques Parizeau, Quebec's then pro-independence premier, bitterly declared his side had been beaten "by money and ethnic votes". More candid Scottish nationalists will admit that this apparent attitude - Parizeau later qualified the remark - has chilled relations between Quebec's PQ and the SNP ever since.

So who exactly are these "new Scottish" voters? And how will they cast their ballots come September?

First, a statistical recap. Roughly 83% of people living in Scotland were born in the country. Natives, literally. Another 10% were born in other parts of the United Kingdom and the rest, some 7%, outside the UK.

This isn't the same as saying how many residents of Scotland regard themselves as Scottish. That figure, according to the 2011 census, is higher, at 88% than the share of people born in the country.

"Where you are born does seem to be a factor in whether you support independence," explains Mark Diffley of Ipsos-Mori. "Notably so."

Ipsos-Mori has carried out eight polls on independence since 2012, the most recent a few weeks ago. In each, it asked respondents where they were born. The result: a sampling size big enough to distinguish between voting intentions on the basis of place of birth without too much quibbling.

Mr Diffley has crunched those figures. His findings? First, that those born in England, Wales and Northern Ireland are far more likely to want to stick with the union than those from Scotland. And, secondly, that those from anywhere else in the world will vote almost exactly the same as native Scots.

Overall, of all those Scottish-registered voters who are certain to cast their referendum ballot, Ipsos-Mori found support for Yes at 33%; No at 56%; and undecided at 11%. However, among non-Scottish UK-born voters the numbers were very different with Yes at 19%; No at a very high 73%; and undecided at just 8%.

Scottish-born voters were keener than average on independence, although Yes support at 36% was still below a simple majority of 53% who would say No. Another 11% were undecided.

That result was nearly mirrored in numbers coming from those born outside the UK and the Republic of Ireland. They were 36% Yes; 52% No; and 12% undecided. Mr Diffley urges some caution on the sample size for non UK-born voters: it was relatively small. But the thrust of the research is clear: non UK-born immigrants feel much the same about independence as those who are Scottish-born. That may make it hard for anyone to make a Parizeau-style claim in Scotland, not least because, so far at least, the majority "native Scottish" population opposes independence.

Mr Diffley's findings also suggest Yes Scotland has a long way to go to convince the half-million non-Scottish Britons in Scotland, many of whom have a vote.

Nick Hopkins isn't surprised. The 40-something dad-of-two and Labour activist has stayed in Glasgow for 18 years. But he is a firm "No".

"I am comfortable calling myself a Unionist," he says, embracing a label not all on the left feel happy with. "The Union Jack means nothing to me, nor does the royal family. I have never worn a bowler hat in my life, never walked behind a band.

"But I am a Unionist all the same."

Nick's family is British, by which, he jokes, he means "a right mix". "I was born in Cheshire to a Welsh father and an English mother," he explains. "I could walk to the border in 15 minutes from my family home.

"My wife Tracy was born in South Wales to a Scottish father. My own daughters, Ffion, who is three, and Lowri, three months, were born in Glasgow. Where am I from? I would say I live in Glasgow but I wouldn't say I was from Glasgow. I would say I was British if I was speaking to somebody from abroad but I'm Welsh on match days. My accent? BBC Scouse."

It's this right mix of an identity that makes Nick worry about independence. "My Unionism is partly emotional because of my mixed family background," he says. "I like the idea of an overarching identity that excludes nobody within my family. To me a Yes vote would fray that. Identities ultimately do depend on there being events, causes, institutions that link people and bind people. Post-indy, those, fundamentally, will go."

A consultant on public policy, especially housing, Nick fears his skills as a Glasgow-based expert may become less relevant to those south of the border if the big change comes. But he worries more about belonging to a new, independent Scotland. "I don't think I would feel the same way about this place if it had said that 'our values are so different from the rest of the UK that we have to go our own route'," he says. "Tracy and I are constantly bashing around the question of whether we would move. We probably would, if there was a Yes vote. I would rather live in a country that was my country. This feels like my country at the moment but I am not sure it would post-independence. More: I don't want to raise my daughters in a situation where their identity is absolutely distinct from mine.

"They could never be foreign. But I like the idea of them growing up with an ID that has a really strong link with mine."

Nick doesn't sense anti-Englishness. Not much, anyway, although he describes how he once watched England play Argentina in a World Cup match in a Glasgow pub. Scotland fans starting chanting: "If you hate the effing English clap your hands!" He clambered on a bar stool and tried to start a rival chant: "If you think Scots are racists, clap your hands!'

"I was quickly pulled down by one of my friends," he says. "But there are feelings there that could be stoked."

Nick reckons the vote will still come down to feelings, many of them unexamined. "I laugh when folk talk as if this is about dry questions of government. There is something deeper in play here than the rules of Holyrood or Westminster."

If it was about such rules, he and his friend Chris Jones might just agree. "You probably couldn't get a slip of paper of his views on most things and mine. But he has gone one way and I have gone the other."

Chris, who lives in Edinburgh, comes from the same north of England Labour background as Nick. In fact, his grandfather is Labour Peer Barry Jones.

Now, after 14 years in Scotland, he campaigns for the SNP.

"When I say I am from the North-east people do wonder what is wrong with my Aberdeen accent," Chris jokes. "But, yes, I am English. I am one of those old Labour people who held their noses when Blair and Mandelson took over the party. But when I came here I found that the SNP suited me better.

"I do understand that there is a kind of Left Unionism that is about working-class solidarity - but I also have a sense of belonging here. Like the North East, Scotland has suffered from policies that were designed only to help the Square Mile.

"There are a lot of English left-wingers who have made the same journey. The SNP is full of them, from the North-east, from all over. It isn't about identity at all."

That would surprise Phillip Charles. Originally from Margaret Thatcher's home town of Grantham, he sometimes still finds himself "defending the former prime minister's honour" to Scots. The 40-year-old has lived in Ayrshire since 1997. But it will still be "foreign" if Scots vote yes.

"If Scotland becomes independent, it becomes a foreign country to the rest of the UK," the ship's navigator declares. "Not that it makes it a bad thing, just as the Republic of Ireland is foreign.

"I don't consider myself English," he says. "I'm British. England is a rugby team, not a country.

"Because I live in Scotland, I would become perfectly eligible for a Scottish passport if Scotland was independent. Whether I would consider myself to be Scottish, I don't know. Nobody could take my Britishness away from me."

The vote is open to all UK, Irish and EU nationals who are resident in Scotland and to all Commonwealth citizens who either have leave to remain in the UK or do not need leave to remain in the UK and who are resident in Scotland.

Tricia Munoz, like Phillip, would take a Scottish passport. In fact, she wants one so much, she is thinking of becoming British so she can vote to try and get one. Chilean by birth, but "Scottish by nurture", she came as a refugee to Edinburgh aged 11 in the 1970s. One of her clearest memories, along with men in kilts and the flower clock on Princes Street, was the first devolution referendum.

"I felt that what happened in '79 was just appalling," the 49-year-old says, referring to the 40% rule that meant a Yes did not count because it failed to secure two-fifths of the total voters' roll. "I so want to be Scottish because that is how I feel. I don't feel British at all. But my problem is in order to get a vote, I would have to become British. I may have to count on my neighbours doing me a favour."

One of those neighbours may soon be Robert Somynne. He is British but he wants to be Scottish. A London primary teacher, the 24-year-old plans to move to Edinburgh to get a vote in the referendum.

"Everybody who lives in Scotland seems to want a different path on things like the country's position in the world or education," he explains, "I want to be part of that."

How do Robert's friends react to his passion for moving to Scotland and being part of a "new" nation? "With bewilderment," he laughs. "If you watch the BBC you would have thought that independence stands no chance, that London subsidises Scotland and you'll have all these preconceptions of the Scottish, of kilts and bagpipes and patronising images of bonny, ginger lassies from the Highlands."

After 24 years in Edinburgh, Maria Conte, originally from Seville in Andalusia, has moved way beyond such tartan cliches. But the arts festival organiser is still torn on independence. She remembers the excitement of Spain's post-Franco "Transition" and wants to feel the same creative explosion that she reckons would come with independence. But she has fear too. "I go one way and the other," Maria says."I would feel like I am a chicken if I don't say yes. It is a chance to create a nation."

But she is also hearing what amount to threats from her own government, hints of a EU membership veto, however unlikely, and what that might mean for tens of thousands of EU nationals.

"That's my doubt about Yes or No, the insecurity as a non-Scottish person, of what effect it would have on me," she says.

"I am resident here. If I wanted, I could get a passport. But I do worry that, if you are a foreigner, you are not Scottish and what this might mean. I am afraid of fierce independentism," she adds.