GORDON Brown entered the EU referendum debate this week with a typically thorough, statistic-laden speech in support of Britain remaining part of the Brussels bloc.

His intervention prompted a few groans on social media from Nationalists who feared his number crunching approach might do more harm than good to the 'In' cause.

But, say what you like about the former Prime Minister, he doesn't use numbers lightly. And one number he used was fascinating.

Scotland, he hoped, would vote by 70 to 30 in favour of remaining in the EU.

That's the kind of overwhelming level of support at which it becomes entirely possible that Scotland could keep the UK in Europe against England's will.

The numbers are tight but, based on turn-out at the last general election, if 70 per cent of Scots vote In, something like 52 per cent of the rest of the UK could vote Out and still be defeated.

Assuming it didn't result in English calls for independence from Scotland (who knows?) such an outcome might cause a shiver of regret among some Nationalists who view the EU vote as the best opportunity for a second independence referendum.

I doubt Nicola Sturgeon would be among them.

As a new discussion paper by Kirsty Hughes, of the pro-EU Friends of Europe think tank makes clear, the prospect of Britain's exit from the Brussels bloc would have huge consequences for Scotland. And, whether the country became independent or remained part of the UK at that point, none of them would be straightforward or particularly appealing.

Take, for example, the scenario Ms Sturgeon described this week as a "democratic outrage": Scotland voting to stay in the EU but being forced to leave as a result of an Out vote across the UK as a whole.

It would indeed provoke a "political outcry," Dr Hughes predicts, and lead to a profound constitutional crisis. But a swift independence referendum may not be the SNP's automatic choice, despite pressure from its own supporters.

For one thing, the prospect of a 'hard' border between a Scotland in the EU and an rUK outside the bloc - the EU's external border, in fact - might make voters think hesitate over independence.

In addition, an independent in-Europe Scotland would face extra costs from not being under the same trading regime as it main trade partner.

Of course, those problems would remain even if the SNP chose to bide its time in the hope of winning an independence referendum at a later date.

With oil prices continuing to fall, some SNP strategists have highlighted late 2020 or early 2021 as a possible date for a second referendum, when they believe their chances could be buoyed by another Conservative general election victory and - thanks to the Tory austerity programme they oppose - Scotland's national debt would be so much smaller.

In that case, the SNP's best option might be to push for a "differentiated relationship" with the EU, something Ms Hughes argues would be possible.

Scotland, although outside the EU, could argue to keep a closer relationship than the rest of the UK with Brussels on a range of issues from agriculture to education. It would make it easier for Scotland to re-join the EU as an independent country at a later stage - though the UK Government might veto the whole idea.

Joining the EU as an independent country at a later stage would also avoid the mind-boggling prospect of simultaneous negotiations on a) the UK's exit from the EU, b) Scotland's departure from the UK, and c) Scotland becoming an independent member of the EU.

However, even if they took place a little later, Scotland's talks with the EU would nevertheless "divert substantial resources" away from establishing the institutions of an independent state, Dr Hughes warns.

Her conclusion is very simple. The "big irony," she writes, is that although Brexit might provide an opportunity for the SNP, independence "would be much more straightforward if the UK remains part of the EU".

The First Minister has said repeatedly she wants the UK to vote In, a comment repeated by her political spokesman during a Holyrood briefing this week. He went further, too, saying she hoped the case she will make during the campaign will resonate not just in Scotland but with voters across Britain.

Far from mourning a missed opportunity, the First Minister will surely breathe a sigh of relief if the UK votes to stay in the EU.