Chris Hanlon, the SNP's former policy chief, who remains a member of the party's policy development committee, has called for a three-way referendum with "devo-max" on the ballot along with independence and the status quo, in what he calls an attempt to break the current constitutional logjam with First Minister Nicola Sturgeon wanting another independence referendum and Boris Johnson failing to agree. 

The suggestion has been received by most supporters of independence with as much enthusiasm as the appointment of Prince Andrew as the patron of a charity which looks after vulnerable teenagers.

The call echoes that made towards the end of last year by Alba party MP Kenny MacAskill who said that a referendum which included "home rule for Scotland" as an option might provide a way to break the "constitutional impasse" in a "deeply divided" nation.

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There are a number of issues with the "home rule/devo-max" option. The first problem is suggested by the fact that even those proposing it don't know what to call it. If they don't know what to call it, far less do they know how to define it.

During her infamous interview with Alistair Darling on Reporting Scotland just days before the 2014 independence referendum vote, Jackie Bird eagerly suggested to the Better Together chief that Gordon Brown's equally infamous Vow, which had just been published in the Daily Record, was "devo-max". Darling agreed that it was. We all saw how that turned out.

The National Wales: The Scottish Parliament building at Holyrood, Edinburgh (Picture source: Mary and Angus Hogg, CC BY-SA 2.0)The Scottish Parliament building at Holyrood, Edinburgh (Picture source: Mary and Angus Hogg, CC BY-SA 2.0)

So just what is devo-max? The anti-independence parties seem to think that it is giving Holyrood control of road signs and some carefully constrained powers over income tax which then Scotland secretary David Mundell described as a "trap" for the SNP. It's clear that the parties of British nationalism think it means as little as they can get away with.

Meanwhile, many supporters of independence think that it means Holyrood should have control over everything, including all tax and revenue powers and immigration, with only defence and foreign policy being reserved to Westminster.

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However, even this more expansive view of devo-max would still leave Scotland outside the European Single Market and Customs Union and Scots would still be deprived of freedom of movement in the EU.

Yet even if all parties could agree on precisely what "devo-max" or "home rule" meant prior to it being included as an option in a referendum, a more fundamental problem is that we would still have to rely on a Conservative-dominated Westminster to deliver it, should it prove to be the option supported by a majority in the referendum. 

The National Wales: This week UK Labour leader reaffirmed his party's support for the Union. (Picture source: PA Wire)This week UK Labour leader reaffirmed his party's support for the Union. (Picture source: PA Wire)

If there is one thing that we all know about the Conservatives and the Labour party when it comes to promises that they make about Scottish self-government, it's that they cannot be trusted.

We can be absolutely certain that they would not act in good faith to implement the decision of the Scottish electorate, and would announce that since the referendum was only advisory they were setting up a Royal Commission which would report back in a few years’ time that Holyrood should get some very limited tax powers, a report which would then go to the Commons whereupon it would be gutted in committees by Conservative and Labour MPs.

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Scotland would eventually be granted the power to vary alcohol and tobacco duties by 1% and Westminster would grandly announce that devo-max had been delivered. 

The "constitutional impasse" that the inclusion of devo-max on the ballot was supposed to overcome would remain very much in place. Meanwhile, years would have passed with Scotland remaining under Westminster rule – years that Scotland could have spent beginning its journey as a newly independent nation.

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