IN less than three months, the SNP will convene in Edinburgh for a special conference to decide the strategy for advancing the cause of Scottish independence.

The party’s national executive committee is expected to publish a motion in mid-January which will then be debated during the gathering.

Ahead of the motion being published, one thing is becoming clearer – those who argue for a de facto referendum must clearly set out how it will deliver an independent Scotland.

Admittedly, I am not a supporter of a de facto referendum. In my opinion, it is a high-risk gamble with little prospect of delivering independence.

Others have already pointed out that the franchise of a UK General Election is significantly narrower than that of the 2014 independence referendum – 16 and 17-year-olds would be unable to vote. EU nationals who don’t have British citizenship would also find themselves disenfranchised. Both of these groups are heavily pro-independence.

To be blunt, the electoral dynamics of a UK General Election makes it difficult for pro-independence parties to win a majority of votes. Of course, the SNP won 49.97% of the vote in the 2015 UK General Election and if you include votes for the Greens, a majority voted for pro-independence parties. So, it is possible that despite these difficulties they could win a slim majority of votes.

Unionist parties have already stated that they do not view the next UK General Election as a de facto referendum and they will presumably campaign on issues other than the constitution. There is no guarantee that voters will respond positively to the SNP and other pro-independence parties trying to fashion an election into a referendum and polling on this issue has been mixed.

If the pro-independence side did win a majority of votes, Unionists would quickly try to question the intentions of the voters, claiming as they do now, that people support parties for a variety of reasons and not solely the constitution.

One thing is certain – if pro-independence parties failed to win a majority of votes, Unionists would claim the constitutional question was settled as there had been two failed votes in the space of a decade.

In this sense, a de facto referendum seems to me to be lose-lose.

Regardless, let us assume for argument’s sake that pro-independence parties do “win” a de facto referendum with a slim majority of votes. What happens next? This is something that has yet to be set out by those who advocate for a de facto referendum.

Will a majority of votes lead to independence negotiations or, as others have suggested, will it be used as a way to pressure the UK Government to negotiate a legally binding referendum as in 2014?

I find it hard to believe the UK Government would suddenly U-turn and start negotiating the break-up of the UK if pro-independence parties were to win a de facto referendum. It might just see it as an opportunity to double down on its intransigence.

Anger within the pro-Yes camp would reach boiling point if a majority of Scots cast their votes for parties committed to an independent Scotland and that went unachieved without UK government acquiescence.

The pro-independence side would then be fraught with internal division, with many demanding a more radical course of action be taken, risking the loss of support from key moderate voters and potentially undermining the international goodwill that has been evident since Brexit.

There is no easy way out of the current gridlock. I believe independence will happen when a sufficiently large and consistent majority of voters agree with our proposition. While the polls after the Supreme Court’s ruling have been encouraging, we must accept there is a possibility the shift towards Yes may be reactionary and unenduring.

Knowing the difference between tactics and strategy is key in politics. A de facto referendum might at first glance seem like a shrewd tactic given the circumstances, but I question whether it fits into the gradualist strategy the nationalist movement has patiently and successfully pursued for decades.

So, as we approach the SNP’s special conference, I hope the motion to be debated will set out clearly how a de facto referendum advances the cause of independence. Activists, but most importantly, the electorate deserve to know.

Marcus Carslaw is an independence activist and vice-convener of the Glasgow Kelvin branch of the SNP