WAY back in early 2007, just as he was preparing to replace Tony Blair, Gordon Brown made his big pitch on Britishness.

The then chancellor - in language that six years later still echoes through Labour's indyref rhetoric - talked of the United Kingdom as a "model for the world of how nations can not only live side by side, but be stronger together but weaker apart."

This was Brown, still considered by some to be too Scottish for No.10, draping himself in a Union flag. But it was also a rallying cry by a future premier against another man who was about to take power, Alex Salmond.

And for this Brown clutched at a word from an altogether different part of Europe, the continent's south-east.

"It is now time for supporters of the Union to speak up," he declared, "to resist any drift towards a Balkanisation of Britain."

Scroll forward to this summer and one of Brown's one-time colleagues, George Robertson, expanded the attack.

"I cannot see why he word 'Balkanisation' is too potent for Scotland's separatists," the former Nato general-secretary told a conference at the Royal Society of Edinburgh. "The dictionary definition of Balkanise is 'divide (a region or a body) into smaller mutually hostile states or groups'.

"That seems to say it all. If the break-up of Britain were to become the model for tomorrow's Europe, then our future would be bleak indeed."

With memories of the carnage of Yugoslavia fresh, this is powerful stuff. Independence, the subtext goes, means trouble; it means hardship; maybe it even means war.

Scottish separatism, Robertson was suggesting, could provoke a domino-effect of instability across the continent.

Experts in the Balkans themselves are, bluntly, not so sure.

Scottish references to "Balkanisation" haven't gone entirely unnoticed in the region. But does anyone in the Balkans think the UK would suffer like former Yugoslavia or the old Ottoman Empire? No, they don't.

Professor Jaroslav Tir, a Croatian expert in post-secession violence, has crunched some numbers to explain why.

He's not surprised that the likes of Brown and Robertson are upset about Scottish independence. He just doesn't think there much of a risk of hostility here.

Let me quote him at length because - although it might sound like he is stating the obvious - I think he's worth hearing.

"Governments around the world don't like the idea of secession because they don't want to lose people and territory," Tir, now of the University of Colorado, told a conference on defence and security at Glasgow University last week. "What interests me the most is the notion that secessions are disastrous because they provoke wars.

"Typically those opposed to secessions list bad news: Palestine is one example; South Asia another; the Irish in the early part of the 20th century; Yugoslavia in the 1990s."

"But let's not ransack history and tear out all the pages that don't fit our story.

"There is another list of secessions: in 1905 Sweden and Norway parted ways peacefully and things are going pretty well in the Nordic world. Czechoslovakia recently split up. Most of the break-up of USSR was fairly unproblematic. And while Yugoslavia has its bad headlines, there were also secessions of Macedonia and Montenegro that were peaceful."

Tir - and this won't be a surprise, even, surely, to Brown and Robertson - reckons any dismantlement of the UK would be more like that of, say, the largely trouble-free process in the USSR than the often fraught one in Yugoslavia. Few, surely, would disagree with him.

This is important: because Tir's research shows peaceful break-ups create very peaceful countries. And Scotland, he reckons, would be unusually peaceful among peaceful states.

"The secession process," he said, "matters." His conclusion: how a state becomes independent seems to determine how peaceful it is. Tir's team have crunched all the numbers for secessions, violent and troubled or peaceful and consensual, in the modern era. He has looked at how many post-Indy states suffered different kinds of conflict, including internal insurgencies or wars over disputed frontiers.

He added: "Peaceful secessions produce very peaceful countries that tend to fight about half the rate of your normal country out there in the world. Violent secessions produce countries that will fight at a slightly higher than normal rate."

But Scotland isn't even in the position of a normal peaceful secession, argued Tir. It is even luckier than that. It enjoys a whole range of other indicators that make it unlikely to get itself into any bother.

The expert said: "Scotland has high levels of economic political development. It as few borders and those it has are well-defined. It is not a major power. Major powers tend to get in to quite a few wars. Basically, from this perspective are not looking bad for Scotland should it decide to secede."

Tir is the first to admit this all seems obvious in Scotland. So obvious that we don't even talk about it. Despite their "Balkanisation" rhetoric, even ultra-unionists would probably concede his point: that an independent Scotland would be an unusually peaceful and safe nation by any international standard.

But Tir reckons we should discuss this matter. Not to do so, he said, would be an "omitted-variable bias", it would be ignoring the elephant in the room.

The expert, after all, was speaking at a conference on defence and security. His contribution obviously raises a question. If Scotland is in such a fortunate position, how much defence and security does it need? Enough to play a modest role as part of an international Atlantic alliance? Enough to defend its industries and state institutions from cyberattacks? Enough to stop it being a base for foreign terrorists targetting neighbouring England?

"Maybe this isn't a surprise," the Croat told his audience. "But it's still worthwhile thinking about this because Scotland finds itself in a unique position. Think about a typical secession taking place in Africa. If we were in one of those places the debate would be probably defined by conversations about whether central government is going to fight back. What is happening in Scotland is rare."

Gordon Brown in his big pitch for Britishness said the UK was a "model for the world of how nations can not only live side by side". But Tir is not the only foreign observer, in the Balkans and beyond, who reckons our "British" indyref is also a model for how nations can decide whether to live side by side.