THIS year we will celebrate the 700th anniversary of the Declaration of Arbroath ... a timely reminder that when the second Scottish independence ref-erendum is held Scotland, we will not be voting to secede from England but to break a 300-year-old union between two nation states. We will be voting to resume a statehood of long standing.

The UK that the majority of voters in the 2014 referendum chose to remain part of no longer exists.

As Labour suffers its worst defeat for decades, the promise of international socialism from the Scilly to the Shetland isles is dead for a decade.

And after 10 years of hamstrung Tory governments, we are now looking at 10 years of majority government from a Tory Party which has espoused such an extreme position that it no longer has room for the likes of Ken Clarke and Dominic Grieve.

That Boris Johnson would be resident in Number 10 was unthinkable back in 2014, almost as unthinkable as Britain leaving the EU.

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The last three opinion polls in Scotland show a majority for Yes, albeit a narrow one. There is still much work to be done until what is a dream for me can be realised. For others, independence is not a dream so much as a possible escape route from the current nightmare of Brexit Britain. However, they still need to be convinced of its merits.

Accordingly, it is incumbent upon those of us who think Scotland’s future is best served as an independent nation in the EU to explain why and how we get there.

Central to the case for independence should be the fact that Brexit has illustrated the limits of devolution and provided a sharp contrast between how small nations fare within the EU as opposed to the UK.

The Brexit process has told Scottish voters a lot about the reality of devolution. It has confirmed, if it were ever in doubt, that power devolved is power retained; that Scotland does not lead the UK but rather must follow where England wishes to go, whether we like it or not.

And that the United Kingdom is not the Union of equals that was described during indyref 2014 but a unitary state where devolved power is taken back to Westminster when convenient.

The distinguished former taoiseach of the Republic of Ireland, John Bruton, has pointed out that Scotland’s marginalisation within the United Kingdom would not happen in the European Union.

In the UK it does not matter what Scotland and Northern Ireland say. They can always be overridden by the English vote. That is not an anti-English comment, it is a comment on the constitution of the United Kingdom.

If an independent Scotland was a member state of the EU, although we are a country of only 5.5 million people, we would have the same veto as Ireland over such a major decision, in exactly the same way as bigger countries.

When looked at that way, the EU seems a rather more attractive future for Scotland than the UK.

However, the fact remains that many Scots wanted to stay in both unions. Scottish politicians from nationalist and Unionist backgrounds worked hard together to fight Brexit but that fight is now lost.

All possible routes for the UK to remain in EU have been completely exhausted. The UK has left the EU.

The argument between a hard and a soft Brexit has been won by those who espouse a hard Brexit.

The only route back to EU membership for Scotland lies via independence. It is therefore the responsible thing to do to discuss Scotland’s constitutional future

This need not preclude Holyrood from addressing challenges in domestic policy. In any event, the road to indy need not and should not be the sole preserve of the Scottish Government or the SNP.

That is why I and others who are keen to win independence for Scotland believe we must reach out beyond the political tribes

So I welcome the First Minister’s announcement of her intention to set up a Constitutional Convention. I believe its membership should include civic society, particularly the trade unions and members of grassroots organisations.

I also welcome the policy papers promised by the FM on Brexit Day. The product of the Citizens’ Assembly will also be of interest.

When I was on the doorsteps campaigning to be re-elected to Westminster in November and December last year, I met many people who told me that they would be voting SNP and that they liked the stance we had taken on Brexit, but that they were yet to be convinced of the case for independence.

Those people voted No in 2014 but Brexit and what came with it was making them look again at their preference for Scotland to stay in the UK. Many of them made it very clear they would vote for independence if it meant independence within EU, but they had questions they felt had not been adequately answered.

These questions revolved around three issues: •The economic case and concern about what currency an independent Scotland will use; •How will the process of accession to EU work? •Can we avoid a hard border with England?

These are all legitimate questions. Much work on answering them has already been done by the Sustainable Growth Commission and in Scotland’s Place in Europe. There is also a rich resource of research and commentary in our universities and think tanks such as the Scottish Centre on European Relations. But this information requires to be packaged and presented to voters in a clear and easily digestible fashion.

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On accession to the EU there has clearly been a sea change. Former president of the European Council Donald Tusk recently struck a very different note indicating enthusiasm and empathy for an application for membership from an independent Scotland.

The National: Donald Tusk: ‘You will witness empathy’ Donald Tusk: ‘You will witness empathy’

He said: “Emotionally, I have no doubt everyone would be enthusiastic here, in Brussels and more widely in Europe, but still we have treaties and formalities. But if you ask me about our emotions, there’s a genuine feeling. You will witness only, I think, empathy.”

He was, of course, careful to emphasise the requirement for the treaties to be obeyed and formalities observed but the nonsense of suggesting Scotland should have to go to the ‘‘back of the queue’’ and be in a comparable position to the Balkan states has been knocked on the head by more than one expert commentator.

We need to work on de-dramatising the issue of border checks between Scotland and England. Any such checks would be for goods only and not people and they would depend on the extent to which England wishes to diverge from the EU and operate an isolationist trade policy.

It is at least curious that the British Government seems so adamant that there will be no checks or controls on the border in the Irish sea between the UK and Northern Ireland but yet there would have to be a hard border with an independent Scotland. Such blatant inconsistency should not go unchallenged.

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Let’s look at how we go about securing an independence referendum which will be legally valid and the result of which will be recognised internationally.

I want to make it crystal clear that I have never advocated a ‘‘wildcat’’ or illegal referendum. Indeed it would be surprising if I had done so given my legal background and the fact that I spent a considerable amount of time last year litigating in Scottish courts and the UK Supreme Court to reverse the effects of unlawful action taken by Boris Johnson.

Ideally, I should like to see an independence referendum take place under the same circumstances as pertained in 2014 under the Edinburgh Agreement.

However, that is dependent on the largesse of Boris Johnson and, frankly, a bald no from him was to be expected, particularly given the likelihood that this time the pro-independence side will win. If we are waiting on goodwill from Johnson it could be a very long wait

The struggle for constitutional change needs to be multidimensional. Accordingly, I would like to see another strand in which, to use the words of the FM, we test the legal case that it might be within the competence of the Scottish Parliament to hold an independence referendum.

The arguments that the Scotland Act can be construed in such a way as to allow for Holyrood to hold such a referendum is well established.

In 2012, before the Edinburgh Agreement was reached, seven legal academics, including three distinguished professors, published a paper challenging the view that only Westminster has the authority to call an independence referendum

More recently, Professor Aileen McHarg and her senior colleague Christopher McCorkindale have reaffirmed this view, pointing out that “although it is frequently asserted that a referendum on independence falls outwith devolved competence ... that issue has never been conclusively settled”.

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My colleague, friend and senior counsel in the Article 50 and prorogation cases, Aidan ONeill QC, has produced a detailed opinion setting out the arguments for Holyrood having the power to do so.

If the Scottish Parliament was to pass a bill making provision for the holding of an independence referendum, I believe the matter would end up before the courts.

It is hard to see it not being the subject of a legal challenge, if not by the UK Government through its law officer the Advocate General – as happened with the Continuity Bill – then by a third party with an interest in seeing such a referendum halted, for example Scotland in Union.

In that event, it would be for the courts to decide whether the bill passed was within the competence of the Scottish Parliament. The case would undoubtedly end up in the UK Supreme Court.

If they found the bill to be within competence, then we would have a lawful referendum which would be hard for Unionists to boycott. If we lose then I do not believe we would be any further back than we are now. And I would expect the UK Supreme Court might have some comments to make about a constitution which does not allow a second independence when the Scottish Parliament has voted to hold one.

Although the courts may play a role in determining the limits of Holyrood’s powers to hold an independence referendum there is, however, no shortcut to an independent Scotland through litigation.

Having Holyrood pass a bill to hold a referendum could be part of a multifaceted strategy which would move us away from the current impasse

Central to that strategy must be providing clear answers to the questions asked by those who have yet to be convinced of the case for independence.

Of equal importance is building a broad coalition of support for independence. Many activists in the Yes movement have been working on this for years.

It is to be hoped that the Constitutional Convention announced by the First Minister can build on and consolidate their work.

The argument is there to be won but the case must be advanced with facts, evidence-based arguments, respect and statecraft. If that is done then I am confident Scottish independence can be won.