Despite the commitment in the United Nations charter to “the principle of equal rights and self-determination of peoples”, independence for new nations rarely comes easily. This week marks the first anniversary of the referendum that led to the creation of South Sudan, the UN’s newest member, but that came only after a civil war that lasted decades and killed maybe million people.

In the developed world it’s usually not quite so difficult — as with this week’s headline case of Scotland, where the regional government is haggling with Westminster over the timing of a referendum on independence. It’s not seriously disputed that if the Scots unambiguously vote to leave the United Kingdom, they’ll be allowed to go.

For now, that seems unlikely — polls consistently show only a minority in Scotland supporting independence. But last year the Scottish Nationalists won an absolute majority in the local parliament, so first minister Alex Salmond has a clear mandate to hold a referendum on the issue. But he wants to do it on his own terms, to maximise the chance of a “yes” vote either then or in the future.

This is where it gets complicated, since opinion within the government in London is divided. Conservatives and Liberal Democrats (and Labour as well) are opposed to Scottish independence, but while the Conservatives never liked devolution in the first place and oppose the Scots getting any more powers, the Lib Dems have supported more comprehensive “home rule” under which Scotland would essentially control its own internal affairs, including taxation, and be subject to Westminster only for such things as foreign affairs and defence.

Salmond’s plan is to take advantage of that by offering home rule as an option in any referendum if he figures that full independence won’t win a majority. That would split the anti-independence forces, and a big vote for home rule might make independence an easier step in the future.

There’s an echo here of the issue that so bitterly divided Conservatives and Liberals a century ago, home rule for Ireland. The difference is that Ireland was always a conquered territory; union with Britain was never popular, and there’s no doubt that a referendum at any time in the nineteenth century would have voted for independence. With Scotland, however, it’s plausible that home rule without full independence would satisfy the majority of the population.

But another thing to have changed in the past 100 years is the development of the EU. Independence is now a less absolute and therefore a less scary prospect; an independent Scotland would remain in the EU and use either the British pound or the euro as its currency, so the differences between that and home rule would be largely symbolic. It would also keep the same monarch as England, just as it had for a century before the Act of Union of 1707.

Apart from the symbolism, the big difference with independence would be the disappearance of Scottish MPs from Westminster. Here the parties have a political interest that conflicts with their policy position: the Tories are most opposed to independence but have most to gain from it, since they rarely win seats there (currently they hold only one of Scotland’s 59 seats), while Labour and the Lib Dems would lose out.

There is also an issue about timing. David Cameron is keen for a referendum to be held as soon as possible, since he seems to have public opinion currently on his side. Salmond, however, insists on leaving it until 2014, to give him more time to make his case and also to coincide with the 700th anniversary of the battle of Bannockburn, when Scotland’s Robert Bruce won the biggest victory in the Scottish war of independence.

Certainly timing matters. Although peaceful secession almost always seems to be later seen as a success (think Norway, Slovakia, Montenegro), some secession movements miss their chance. West Australians actually voted 66% for secession in a 1933 referendum, but at the same time they elected an anti-secessionist Labor government; the issue was allowed to die and, despite occasional revivals, it never really looks like happening. Quebec may have missed its opportunity as well, with a narrow vote against independence in 1995 having led to a sharp decline in the independence movement.

Alex Salmond wants to be remembered as the founder of a new nation, but if he lets Cameron outmanoeuvre him on a referendum, then it could be a long time before Scotland gets another chance.