We must thank Nicola Sturgeon for removing any doubt that the SNP is going to relaunch the campaign for independence over the summer.

There can only be one reason for the sense of urgency: Ms Sturgeon is aiming to secure the second referendum before the end of the decade.

At least one SNP strategist has argued the right time for the vote would be after the Westminster elections in 2020, when the Tories are favourites to be re-elected yet again.

But the logic of going for independence before then is overwhelming. And it doesn’t require a Brexit vote on June 23 this year to make the conditions for that vote much more favourable.

Think of where we might be in 2019. The Tories are likely to have lost their small majority, and be subject to the constant threat of Parliamentary defeats from a loose Labour-SNP tactical alliance – just like the one Ms Sturgeon demanded from Ed Miliband. Will the UK Government be powerful enough to resist demands for a second referendum at this point?

David Cameron will almost certainly be gone, to be replaced by Boris Johnson or George Osborne. Ms Sturgeon must be praying for the latter. If Mr Cameron is viewed in Scotland as a distant and shallow Viceroy, Mr Osborne, if he ever dared to set foot over the border, would be greeted like some kind of Sith Lord, complete with pantomime booing. The Chancellor appears to have no emotional attachment to the Union and, if the rumours are true, actually argued the case internally for Scotland to be cut adrift last time around.

And then think about Ms Sturgeon’s personal position. The next four years are very likely to be the peak of her political career. Who knows what will happen four years from now. Can the SNP continue to defy the logic of the Holyrood voting system and win yet another clear victory? Will Ms Sturgeon still be the leader? At the very best, all of this is very uncertain.

So the time is now to go for that second referendum. But here’s the thing: I think Unionists should embrace the idea rather than being seen to "deny" Scots their democratic rights.

Ruth Davidson is wrong to claim that it’s time for Scotland to "move on". Whoever you want to blame, independence is clearly unfinished business. The burning sense of grievance that followed Mr Cameron’s disastrous People of England speech will not go away until that second referendum happens.

But that’s where I see the opportunity for Unionists to settle the question once and for all.

Let’s assume a very optimistic scenario for the SNP by 2019. The tectonic plates of UK politics have shifted in their favour, as I have already described. Let’s go even further, and assume Mr Osborne, desperate to save his Premiership, drops his opposition to an independent Scotland keeping Sterling.

That still leaves two huge obstacles in Ms Sturgeon’s way.

First, she has to pray that the forecasts of the International Energy Agency (IEA) are correct and the price of oil will be heading back to $80 a barrel by 2019. As this year’s Scottish budget has painfully revealed, there is no economic case for independence without a resurgent North Sea industry. But there are many sound reasons for believing that forecast is wrong.

Second, there would have to be a complete volte-face on behalf of the various leaders of the European Union, from the President of the Commission to the Prime Minister of Spain, in resolutely opposing the idea that an independent Scotland can keep its membership of the EU, or walk straight back in. Given the continuing threat of separatist movements in Spain and other member states, I just don’t see this happening – ever.

And finally, there is the opportunity for the Unionist side to demand "Southern Scots" – those of us who live in other parts of the UK, should be given a vote. If British citizens who have lived in Europe for 15 years or less can vote in the EU referendum, why should I, as someone who was born and bred in Scotland be denied a say, just because I happen to be south of the border at the present time? This is my country just as much as it is Ms Sturgeon’s or Alex Salmond’s.

Unionists should be encouraging the SNP to achieve their goal of a second referendum, as former First Minister Henry McLeish argued in The Herald yesterday. And when they lose again, this time it’s really over. Final. Finished. No more. And with all those years of uncertainty over and done with, it will be time to focus the real goal: making Scotland the much more prosperous country that it needs to be.