POLITICAL soundbites and slogans are at their best when offered alongside a credible plan. They are a headline to the flesh and bones of considered policy. Without the substance that underpins them, political slogans can be frustrating for voters.

When we think back to the EU referendum, one phrase – seared in our collective memory through the force of repetition – immediately springs to mind.

“TAKE BACK CONTROL.”

It is easy to scoff now, as we look on in horror at our political class veering from one Brexit disaster to the next, but we shouldn’t underestimate the power of those three words in their ability to neatly encompass the arguments of their proponents.

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At its core, “TAKE BACK CONTROL” was an emotional argument, made even more successful by its deliberate vagueness.

Leave politicians sold it as three central promises: “Take back control of our laws, our money and our borders.”

The detail that should have accompanied it – of precisely which EU laws the UK wanted to scrap, of how areas and projects which rely heavily on EU funding would be supported in the future, and the detail of our new immigration policy – was sorely lacking.

Such vague sloganeering may helped swing it for the Leave campaign, but it has arguably led to the confusion and competing versions of Brexit that we are now struggling through.

There’s a lesson there for those who support independence for Scotland.

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Nicola Sturgeon has said that she will lay out her plans and thoughts on indyref2 in the coming weeks. When the time comes to fire the starting gun, the central message that SNP politicians converge around – as the most prominent salespeople of the merits of independence – will be critically important. Of course, it must also be backed up by a comprehensive White Paper which sets out the detail of our future direction as well as addressing the concerns that No voters had in 2014.

Watching SNP MPs and MSPs speaking about indyref2 in media interviews, you get the sense that the all-important hook has not yet been agreed.

We know that when Sturgeon formally requests a Section 30 order Theresa May will – initially at least – refuse. She even has a handy slogan for that: “Now is not the time.”

The knowledge that the UK Government neither cares about nor acknowledges the mandate for indyref2 that was won in the SNP’s 2017 election manifesto and the subsequent vote in the Scottish Parliament should focus the minds of those who think that a concise pitch is an optional extra.

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We’ve often heard SNP politicians use the “lifeboat” metaphor. Some point to the existing mandate, others speak about Scotland controlling its own destiny. Many reference Scotland being taken out of the EU, despite the promises made in 2014 and our 62% remain vote in 2016.

In a recent speech, SNP MP Peter Grant framed indyref2 as a “choice between two unions”. He made the case that Scotland has had two constitutionally significant referendums, the outcomes of which are in direct conflict with each other.

Joanna Cherry and other SNP bigwigs have also advanced a similar argument in recent weeks: that we can’t remain in both the UK and the EU, as is our expressed will, and voters should have the chance to choose between them.

“A choice between two unions” seems to tick all the boxes. It is easy to understand, clear and memorable. It opens a conversation about the existing mandate for indyref2 and the circumstances in which that was won. When the referendum campaign begins, it allows for a positive broader message in keeping with the vibrancy of 2014. The No campaign won’t simply be able to rely on why Scotland “can’t” be independent – they will also have to sell the benefits of the Union of the UK against all the advantages of EU membership.

There are those who are understandably reluctant to entangle the arguments of independence with the clusterfuck of Brexit for fear that the case for independence will be dulled when argued alongside our membership of the EU.

Like it or not, the two are entwined and will remain so for the foreseeable future. In the political battle ahead on the issue of a Section 30 order, the SNP must use disciplined and consistent messaging to counteract the risk of muddling the two big political questions that Scotland faces.

The point at which a slogan becomes successful is when journalists use it when questioning those in opposition to the cause it is advocating and when members of the public use it – unprompted – during vox pops and phone-ins. And ultimately, when the arguments and detail behind the central message are known outside of its core voter base.

I’m sure that behind the scenes there will be many focus groups and discussions with strategists on exactly what form of words the all-new-and-improved independence pitch should take. Personally,

I think Peter Grant has nailed it. It’s a choice between two unions.

Scotland, take your pick.