UN peacekeeping forces were moving into position last night as the inhabitants of Berwick declared independence from England. Secessionists are insisting that opinion polls confirmed that the majority of the population wished to leave at the earliest opportunity and become part of recently-independent Scotland. Amid scenes of jubilation in the border town, there are anxieties about the fate of the remaining ethnic English still living in the disputed zone.

The Prime Minister David Miliband said that the Berwick move was "a flagrant and unilateral act of secession by a part of the territory of England and illegal under international law". The British government has reacted with fury to the call of the Russian President, Vladimir Putin, for all "free peoples" to recognise the right of Berwick to self-determination. America has condemned the Berwick Liberation Front as "moral terrorists" and pledged to lend air support if English nationals are ethnically cleansed from the area. But the European Union has announced it is willing to open a mission in Berwick to ensure there can be a peaceful transition.

All fantasy, of course. Berwick's people are much too sensible to take up arms, even if a majority have, apparently, voted to leave England in a referendum organised by the ITV Tonight programme. However, Kosovo is a sobering reminder of what happens when nationalism gets out of hand. And no, I'm not going to make any facile comparisons between the Scottish National Party and the Kosovan Liberation Army or any other militant nationalist grouping. The SNP is a civic nationalist organisation, dedicated to democracy, which has stamped down hard on anti- English sectarians. OK?

Mind you, most nationalists would be happy to see Berwick restored to Scotland and SNP MSP Christine Grahame has tabled a motion to the Scottish Parliament calling for Berwick to "return to the fold". It's not inconceivable that, if Scotland were to become formally independent - an eventuality that is no longer being regarded as fantasy in Westminster - there could be genuine border disputes over areas such as Berwick, which "feel" Scottish, even if they have been part of England for 600 years.

It is one of the reasons why Unionist politicians insist that independence would be divisive. No matter how amicable the divorce between England and Scotland might be initially, when it came to dividing the geographical assets tempers could get frayed. The SNP responds that, in Berwick as in Kosovo, you have to give people the right to decide, by majority vote, which country they wish to be part of. The right of free peoples to self-determination is inviolable and enshrined in international law.

True, of course. But who decides who "the people" are? The Kosovan Albanians may have voted for independence, but Kosovo is still legally part of Serbia, which would vote for the province to remain so - if anyone asked. As we know from bitter experience in Northern Ireland, when you start chopping up states and handing autonomy to oppressed ethnic groups, they have a nasty habit of becoming the oppressors themselves.

The Serbians may have behaved atrociously, trying to "ethnically cleanse" the Kosovo province of ethnic Albanians in the 1990s, but that doesn't excuse the way the Kosovars have treated the Serbian minority since the end of the war in 1999. Human Rights Watch has issued an urgent call for protection for the Serbian minority in Kosovo, which has been the subject of large-scale violence since 2004, when 60,000 Kosovan Serbs were driven from their homes by Albanian militias. Many were murdered. Some 200,000 Kosovan Serbs are still living in camps abroad, unable to return to their homeland.

It would be ironic, indeed, if the west had to intervene in Kosovo for a second time in 10 years to prevent the ethnic cleansing of the Serbs. The dark side of nationalism has never been darker than in the Balkans. In the maelstrom of nationalisms that proliferated after the collapse of the Yugoslavian state, it's not easy to identify the good from the bad, the right from the wronged. All the more reason, then, to ensure that, if Scotland does become independent, it is done in a civilised and humane manner. Now, there is no reason to suppose that the process of Scottish independence, were it to happen, would be any more "conflicted" than the separation of Slovakia from the Czech Republic in the 1993. That velvet divorce has become the template for all civic nationalist movements in Europe. There was a bit of fuss about the division of the Czechoslovak national debt, and whether or not to have separate currencies, but in the end the two sides sorted themselves out, and made a go of it. Indeed, the five million Slovaks - who were very much the poor relations in the old Czechoslovakia - have never looked back. Slovakia is now one of the fastest-growing countries in Europe.

Most of us would assume that Scottish independence would take the Slovakian route, rather than the Kosovan. We do not have a Balkan history of ethnic conflict, dictatorship, war and partition. Our wars of independence ended in, er, Berwick hundreds of years ago. Moreover, participation in the European Union would likely ensure a more civilised secession than in the Balkans.

Of course, there are still those who say that Europe would refuse to admit Scotland if it became independent. Some Labour ministers have argued that countries such as France would block Scotland's membership for fear of encouraging regional separatist movements in their own countries. But as in Kosovo, I suspect the EU would be among the first to recognise an independent Scotland - especially as it would be eager for the euro. There is realpolitik here. The diplomatic advantage to countries such as France from the disintegration of the UK would outweigh the risk of provoking domestic nationalism.

Think of it. Great Britain would be no more, its influence in the European Council fragmented, its place in the UN Security Council in question and its stature among the community of nations hugely diminished. England may be the biggest bit of the UK, but the loss of the little bits could be highly damaging to its international prestige. Indeed, my own view is that Westminster - if it were sensible - would plan for a historic compromise with Scotland, giving it all the political autonomy it sought so long as it remained formally part of the UK in the eyes of the world.

We would be living apart together; keeping up appearances, while going our separate ways politically. Scotland would remain British under the crown, a nominal partner in a new confederal United Kingdom. And if that meant handing Berwick back, I suspect the English wouldn't think twice about it.