Will leaving the EU lead to Scottish independence and the break-up of the UK?

The big EU questions: With only weeks to go before the potentially epoch-making vote on British membership of the EU, the debate so far has been characterised by bias, distortion and exaggeration. So from now until the referendum we will be running a series of question and answer features that will explain the most important issues involved in a detailed, dispassionate way to help inform your decision

'Alex Salmond, the former SNP leader, has suggested that a second referendum would be held within two years of a Brexit vote and that Scots would vote Yes' (Getty)

Why are we asking this question?

Opinion polls suggest that a majority (54 per cent) of people in Scotland want to remain in the European Union, with 32 per cent wanting to leave and 14 per cent saying “don’t know“. If the UK voted to leave in the 23 June referendum, it would reopen the debate on whether Scotland should become independent. (This is not the only scenario: another is that England could vote for Brexit and be outvoted by Scotland, Wales and Northern Ireland).

Haven’t the Scots just voted to remain part of the UK?

Yes. In September 2014, they agreed by 55 per cent to 45 per cent to remain. The Scottish National Party says the Scottish Parliament should have the right to hold another referendum after a “material change in the circumstances” – such as Brexit against Scotland’s wishes – or “clear and sustained evidence that independence has become the preferred option” of most Scots. SNP sources suggest this would mean 60 per cent support for a year.

So would it be better for the SNP if Scotland votes to stay and the UK opts for Brexit?

Possibly. Alex Salmond, the former SNP leader, has suggested that a second referendum would be held within two years of a Brexit vote and that Scots would vote Yes to independence this time. Nicola Sturgeon, the current SNP leader and First Minister, says there would be a “real chance” of a second independence referendum in these circumstances, but insists this is “a scenario I will be doing my best to ensure doesn’t happen” because she wants the UK to remain in the EU.

However, some Remain campaigners claim that Ms Sturgeon is playing a double game —appearing to oppose Brexit while subtly doing what she can to bring it about.

If the UK voted for Brexit, Ms Sturgeon would come under strong pressure from her own party to secure a second referendum. But she wants one only when she is sure of winning: a second defeat would almost certainly kill the issue for a generation.

Would the UK Government give Scotland another independence referendum after a Brexit vote against its wishes?

Unlikely. The SNP might need to win a mandate at the 2020 general election or the next Scottish Parliament elections in 2021. But public pressure in Scotland could build. The Green Party would back a second vote, giving the SNP a majority on the issue in the Holyrood Parliament.

Is support for Scottish independence still on the rise?

No. Falling revenues after the oil price collapse have raised doubts about whether the Scottish economy could survive on its own. Some observers think the SNP may have peaked. Although the party retained power at the Scottish Parliament elections in May, it lost its overall majority. The Conservatives leapfrogged Labour into second place on a pro-union platform, amid signs that some voters are tiring of the independence debate and want the SNP to get on with running the country.

According to the What Scotland Thinks website, the latest polls suggest that 41 per cent of Scots would support a breakaway now, while 48 per cent would vote No (figures exclude don’t-knows). After a Brexit vote, 44 per cent would back independence, and 47 per cent would vote No.

Is anyone saying that the UK could break up if Scotland is outvoted on the EU?

David Cameron has warned that leaving the EU could lead to the “disintegration” of the UK. In Tuesday night’s Sky News debate, he said he was “worried” about the prospect of a second referendum.

Sir John Major, the former Prime Minister, said there would be “a high probability that Scotland will hold another referendum and leave the UK, and as a result the UK would be fractured“. The House of Lords Select Constitution Committee has warned that the referendum poses a risk to the union.

But Jim Sillars, a former SNP deputy leader, said many Scots would balk at an uncertain future if the rest of the UK left the EU. “I don’t think it stands up to very serious analysis,” he said. One scenario is an increasingly fractious Union, but one that does not break apart.

Could there be a constitutional crisis after a Brexit vote?

Possibly. The legislation governing the Scottish Parliament says it cannot pass laws incompatible with EU law. A clean break with the EU would require these laws to be amended, which would normally require Holyrood’s consent. It might refuse. Imposing change from Westminster could spark a crisis, some experts say.

Would an independent Scotland be allowed to join the EU?

There was confusion during the 2014 referendum over whether an independent Scotland could remain in the EU or would have to apply for membership, how long that might take and what terms would apply. There are signs of “enlargement fatigue” in the EU and five would-be members are already in the queue. In practice, Scotland might secure fast-track entry.

Nicola Sturgeon reacts after a positive result for her party at the Emirates Arena in Glasgow (EPA)

What problems might there be?

New EU states are supposed to sign up to joining the euro and independent Scotland could lose the UK’s opt-out. The SNP wants to keep the pound, but the UK Government ruled that out during the 2014 referendum. Trade between Scotland and the rest of the UK would be covered by the deal struck between the EU and the UK. Scotland exports £48.5bn to England, Wales and Northern Ireland, and only £11.6bn to other EU members. (Figures exclude oil and gas.)

How is the EU debate going in Scotland?

The SNP is running its own Remain campaign and not sharing platforms with the Conservatives. The SNP has accused both sides of “threats and fearmongering” and called for more a positive In campaign. Labour and Liberal Democrat figures have accused the SNP of undermining the pro-EU cause, warning that talk of a second referendum could encourage some Scots to vote for Brexit.