Scottish independence
Alex Salmond may have resigned - but his cause lives onReuters

From the moment it became clear that the anti-independence campaign had secured a modest win, people in the Yes camp started asking themselves : "Will we get another chance? If so, when?" Well my instinct is to advise the SNP to be cautious on this question, because we know from Quebec that there is indeed a public tolerance for a repeat referendum on independence, but only if the circumstances and timing are right.

In the mid-1990s, some 15 years after Quebec had rejected self-government by a substantially larger margin than we saw last night, the Parti Québécois (PQ) was returned to power on a promise to hold a second referendum, which it came within a hair's breadth of winning. That happened because the rest of Canada had failed to meet the promise of a constitutional settlement that reflected Quebec's national aspirations, and it's scarcely inconceivable that history is about to be repeated in this country.

But since the narrow second failure in 1995, the PQ has been caught in a trap it can't seem to escape from. Earlier this year, it was heavily defeated in a provincial election it had initially looked likely to win, after voters recoiled from what seemed to be hopeless uncertainty over whether the party actually intended to hold a third referendum or not. It seems to me the lesson is that clarity is at a premium – voters must always know when a vote for the SNP is a vote for a referendum, and when it is no such thing.

I would imagine that for the next two Holyrood elections, the SNP will make clear that they remain committed to the medium-term goal of independence, but that in recognition of the legitimacy of last night's result, that goal will not be pursued over the forthcoming five-year term of government. But just as importantly, when a judgement has been reached that enough time has elapsed (perhaps because the public continue to be dissatisfied with the weakness of the devolved settlement), the proposal for a second referendum must be absolutely unambiguous.

In particular, the timetable will be crucial. A very long campaign was entirely appropriate on this occasion because the arguments for independence were so unfamiliar to a lot of people, but that won't be the case next time. The public would be most likely to favour a short, sharp campaign that would be over and done with very quickly – and, as it happens, that was precisely the option that was pursued in Quebec in 1995.

There is one important exception to what I've just said, however. If the United Kingdom votes to leave the European Union in the in/out referendum promised by the Conservative party, and if Scotland votes to stay in but is forced to leave anyway, then it's possible that the public may feel that the terms on which they voted against independence yesterday no longer apply.

After all, the (bogus) argument that a No vote was the only way to keep Scotland in the EU was a key part of the anti-independence campaign's pitch. The SNP would still have to be careful to ensure that it was not running ahead of what the public is willing to tolerate, but it's conceivable that in those circumstances there might be considerable sympathy for a much earlier repeat referendum to get an independent Scotland back into the EU (and out of a Tory/Ukip hell-hole) as soon as humanly possible.

Scottish Devolutions on Track Despite Salmond's Claims No Voters Were 'Tricked'
Flares are let off while pro-union protestors clash with pro-independence protestors in Glasgow's George Square on 19 SeptemberReuters

Electoral suicide

I gather that some parts of the Westminster establishment think that they've been fiendishly clever, and have prevented the SNP from even making the choice to hold another vote. The thinking goes that the Edinburgh Agreement only transferred the legislative power to hold a referendum on a one-off basis. But the reality is that the SNP always believed they had the power to hold a consultative referendum without "permission". It would be electoral suicide for any London government to attempt to remove that power, after explicitly pledging that a No vote would lead to more powers coming to Scotland, not less.

And, ah yes, the pledge. The "vow". There was a faintly comical incident on the BBC Scotland results programme when Labour's Kezia Dugdale, at a point when it looked like the No campaign were heading for a more substantial margin of victory, innocently tried to claim that no-one had ever said that a No vote was a vote for more powers for the Scottish Parliament. If that line had held, it would have marked an even speedier breaking of a "solemn vow" than Nick Clegg managed on tuition fees.

Fortunately, the tide turned in the results and Yes ended up taking the big prize of Glasgow, along with a formidable 45% national share of the vote – at that kind of level it's simply not credible to argue that Scots were not voting for substantial change, particularly given that many No voters will have made their decision on the basis of the "vow". There does seem to be an acceptance of that reality across the three London parties today.

But will the actions match the rhetoric? Depressingly, I fear not – but that's a problem for London every bit as much as it is for Scotland. The example of Quebec shows that if promises are not kept, a second referendum is not merely possible, but likely. The Scottish pro-independence movement will be better-placed than their Quebec counterparts to get over the line at the second time of asking – we'll be starting from a higher base of support, but we also have the advantage of a much less polarised society.

In 1995, a substantial 60-40 majority of French-speakers voted for Quebec sovereignty, but the Yes campaign still lost because Anglophones and allophones (those whose first language is neither English nor French) were almost unanimously against. By contrast, the YouGov exit poll shows that well over 30% of people who were born outside Scotland voted for independence yesterday. The Scottish-born population were split 50/50, and if that was to move to a 60/40 split in a second referendum, the contest would be won easily.

In 1979, the people of Scotland failed to vote decisively enough in favour of devolution in a referendum. Margaret Thatcher's incoming government misinterpreted the result, taking it as a green light to impose an almost colonial form of rule on the country. The subsequent outrage led directly to the 1979 outcome being overturned in a second referendum eighteen years later, and to a Scotland Act that started with the words "There shall be a Scottish Parliament."

If the Westminster establishment fail to rise to the challenge on this occasion, don't be surprised if we eventually see an Act of Parliament that starts with the words "Scotland shall be an independent country" – and perhaps even in the not-too-distant future.

James Kelly is author of the Scottish pro-independence blog, SCOT goes POP! Voted one of the UK's top political bloggers, you can hear more from James on Twitter:@JamesKelly