Scotland leader Nicola Sturgeon is a 'canny' politician who would not promise something she could not deliver, according to Dr Catterall. Jeff J Mitchell / Getty Scotland is very unlikely to get another independence referendum, says constitutional expert Peter Catterall of Westminster University.

This is because it would be hugely "messy" on a political level and because the Scottish economy simply cannot handle a secession right now, he told Business Insider's Lianna Brinded in a Facebook Live interview.

In 2014, 55% of Scots voted to stay in the UK while 45% pipped for independence.

However, Scottish National Party leader Nicola Sturgeon has been gunning for another independence referendum, since Scotland overwhelmingly voted to remain in the EU referendum (62%) while Britain as a whole voted for a Brexit.

Catterall did say, however, that Scottish National Party leader Nicola Sturgeon was extremely "canny" and that she was the only politician who had risen to level the events demanded in the wake of the Brexit chaos — which saw Prime Minister David Cameron resign on Friday and both of the UK's main political parties scramble to secure their positions.

Here are the main problems with a Scottish independence referendum:

Westminster may not even allow it

First things first: Scotland may have its own parliament, but to hold a national referendum it still needs permission from Westminster in London. Over 55% of the country voted to stay in the UK in the last independence referendum in 2014, undoubtedly a healthy margin which surprised expectations.

But following a decisive Scottish vote to remain in the EU, the post-Brexit anger in Scotland could be enough to make Westminster politicians think twice about allowing another independent Scotland vote. And there is no constitutional obligation for the UK government to allow it to happen, Dr. Catterall says:

"The argument the UK government may put forward is that it needs to approve a second Scottish referendum and could, in theory, withhold the consent. When the Americans wanted independence in 1776 they did it by violence. We don’t want that — we want to follow constitutional procedure. The question then becomes, how far do you push against the inevitable?

"Nicola Sturgeon - said she would advise Scottish parliament to vote against leave resolutions. That is in her right to do so. Scotland voted solidly against Leave, so it’s unreasonable for her to do anything else. Democratic rule says we have to respect the will of the people, but what people? The British people? The English people? The Scottish people?"

Dr. Catterall adds that while Sturgeon is being smart about how she plays post-Brexit politics, the EU may also have problems with an independent Scotland joining:

"Sturgeon is the only politician who comes across as someone with a plan. She’s sending out a signal to the Scottish people — we hear what you have said — and she’s sending out a message to Westminster and Brussels. There is also a risk that EU members, particularly the Spanish, would not like to see Scotland secede because areas like Catalonia may follow suit."

Scotland's economy cannot handle independence

Another consideration is that Scotland might not even be able to afford to be independent right now — and Nicola Sturgeon almost certainly knows it. As Dr. Catterall says:

"[Scotland's] economy has moved since 2014's independence referendum. The oil price has changed, the exposure of major Scottish banks has become even worse as we’ve seen with the RBS share price recently, so I suspect that what Sturgeon is doing is exploratory talks. She’s a cautious, canny politician. I was struck by the way she got Alex Salmond, rather than herself, to work the TV studios and make the noises. This gives her plausible deniability. Unlike Boris Johnson, she is unlikely to say something she doesn’t think she can deliver on."

Scotland's claim to North Sea oil was major factor in the pro-independence campaigners' manifesto, but oil has more than halved in value in the last year and a half, as has the share prices of RBS which had to be rescued by the British government after the 2008 financial crash — further complicating any talk of Scottish secession.

Scotland's economy has grown far more slowly than the rest of the UK as a whole since the last recession, the Guardian notes, with just a 4% GDP growth compared to the UK economy as a whole which grew 23% in cash terms. This is not the picture of a country ready to go it alone, even with the EU membership it already enjoys.

Agreeing on what kind of independence Scotland gets will be almost impossible

Even if Scotland could get an independence referendum, the manner of that independence is going to be really hard to agree on— much like the headache Westminster is having at the moment trying to figure out the Brexit. As Dr. Catterall makes clear, the EU already has a few examples of members with non-standardised arrangements, and finding one that suits the majority will be tough:

"There are a number of halfway houses. Take Denmark: it is in the EU, but two parts of Denmark — Greenland and the Faroe Islands — are not in the EU. Is this a model for Scotland? The answer is: nobody quite knows. It will be a matter for politics. What we do know is that it worked for Denmark and even Germany getting the East half in around the time of reunification, so it’s certainly not impossible to conceive an asymmetric UK in which a semi-autonomous Scotland is in the EU and rest of mainland Britain isn’t. But in practice, it would be very messy to establish."

Two major things Scotland will have to decide before another independence referendum is whether to join the Euro currency — maybe not a bad idea after the pound just got annihilated — and the little matter of joining the Schengen agreement, a treaty which effectively abolished border checks for member nations.

Whatever Scotland decides, the signs currently suggest it wants to keep its EU option open. Alyn Smith begged the European Parliament this morning to "not let Scotland down," making it clear that whether it gets its unlikely independence referendum or not, it still sides with Europe: