EXACTLY a year ago today campaigning in the independence referendum was reaching a crescendo. Prime Minister David Cameron used a speech in Aberdeen to warn Scots faced a "painful divorce" if they voted Yes. First Minister Alex Salmond staged an event at Edinburgh airport where he hit out at the "scaremongering" of the No campaign.

The day had begun with a poll of polls showing a 51 to 49 per cent lead for No. It ended with the first edition of the Daily Record revealing "the vow," a promise of more powers for Holyrood signed by Mr Cameron, Ed Miliband and Nick Clegg.

The sheer intensity of those final few days before the vote is just a memory now but the debate over Scotland's future has not faded a bit. Far from it. The referendum has continued to shape Scottish, and UK, politics over the past 12 months in dramatic fashion. Over the next few days, The Herald's political journalists, those of us who were immersed in the campaign a year ago, will consider its impact.

Today the big question for many, especially those new SNP members whose political activism was forged in the remarkable grassroots campaign for a Yes vote, is when can they do it all again?

Their appetite for a second referendum, whetted further by recent polls showing a majority in favour or independence, presents First Minister Nicola Sturgeon with a dilemma.

Her own approach is cautious, a tacit acknowledgement that the economic case for independence is weaker than a year ago. The price of oil has halved. The Scottish Government's own figures suggest Scotland would be £8.6billion worse off if the country were to become independent in 2016/17, the timescale promised by Alex Salmond, than it would be as part of the UK. The question of an independent Scotland's currency also remains unresolved, with a growing number of prominent Nationalists beginning to question the former First Minister's plan for monetary union with the rest of the UK.

Ms Sturgeon knows she must play a longer game. She must use the next five years to govern effectively at Holyrood while allowing unpopular Conservative policies at Westminster to fuel demands for independence. The First Minister can avoid making an unconditional promise of a second referendum during the next Holyrood parliament. But after 2021? Her party will not be so patient.

The hunger for a second poll among Yes activists is matched only by the complacency on the part of the pro-UK parties, who watched the SNP retreat from its demand for "full fiscal autonomy" and quickly returned to lick the wounds they suffered during the general election.

Blair Jenkins, the former head of Yes Scotland, made a telling point in an interview with The Herald to mark the referendum's anniversary. The simple fact so many Scots declared their support for independence last year had been "transformational," he argued. A new independence campaign would start with support at 45 per cent at least.

Mr Jenkins's best guess is that a second referendum will be held not long after 2021. He might be right. I'm pretty sure he hasn't thrown his campaign posters away.