A "Yes" campaign poster is displayed on the Isle of Lewis in the Outer Hebrides September.

Thursday's vote in Scotland is a truly amazing historic phenomenon. The people of Scotland are being accorded the right to choose to peaceably secede from the United Kingdom of Great Britain and Northern Ireland. The people of Northern Ireland already have that right but are unlikely to exercise it in the very near future. The UK has truly become a conditional entity.

More than four million Scots are entitled to vote, and voter registration suggests that there will be a high turnout.

Of course, opinion polls are one thing; actual voting is another thing entirely.

We only have to remember that the outcome of our Seanad Referendum a week from polling was a foregone conclusion, according to the pollsters, to remind ourselves that there is a world of a difference between indicating "soft" support for or against a proposition on your doorstep and going out to vote for it in a polling station.

In the Seanad referendum, opinion polls suggested a very high intended turnout (more than 80pc) but polling day saw half that number actually voting.

In the end, opposition to abolition of the Seanad was a much "harder" vote than the abolitionist vote.

The issue in Scotland will be decided by the "hardness" of conviction voters on the day; it will be a tussle between the head and the heart.

My personal preference for the Scots is for a "Yes" vote. Why?

I think that Scotland, like this part of Ireland, will be immensely more successful and more fulfilled by taking the path of independence. I agree with Garret FitzGerald's view that independence has been hugely positive for Ireland. Economically, socially and culturally, we have prospered in a way that simply would not have happened if we were a province in the United Kingdom. I think the same will be true for Scotland.

Post-industrial Great Britain is increasingly the state of the Great Divide. The metropolitan south-east is breaking away from the rest of the island along a line of tectonic fracture which goes from the Severn to the Wash. On one side of the line is post-industrial decay; on the other is a dynamic financial entrepot. On one side there is hope and confidence; on the other lies a sense of inexorable decline. The High Speed Rail project (HS2) is designed to anchor the process of drift in the midlands. But no-one is proposing to build it to Glasgow.

Scotland's national future, I think, needs independence.

Of course, the British Establishment is now belatedly offering a promise of Dev Max to buy off independence. Why did Cameron keep it off the ballot paper only to offer it as a desperate game-changer when the postal votes had already been cast?

Can that promise be taken seriously? Read Ronan Fanning's work The Fatal Path to judge how sincere or insincere the British Establishment can be when making "Home Rule" promises.

In truth, the referendum is more a crisis for England.

Issues such as currency sharing and EU membership are being raised by those in London whose real fear is their own incapacity to believe in a future United Kingdom of England, Wales and Northern Ireland. It looks so wholly improbable that it must send a shudder of fright through Westminster and Whitehall.

Such a United Kingdom would stand diminished on the international stage. By irony, London needs Scotland far more than Scotland needs London.

That is why the parties at Westminster from the Tories, the Liberals, Labour to UKIP all need a "No" vote. Scotland is indispensable to their self-image internationally. To them, Britain means much more than England with Wales and Northern Ireland tacked on.

The British media simply do not want to become the media of England and Wales. Hence their relentless pursuit of a "No" vote.

The notion of England, Wales and Northern Ireland exiting the EU, while Scotland and Ireland stay on seems faintly ridiculous. The much-promised "In-Out" referendum looks like a joke if it takes place in England, Wales and Northern Ireland. It looks like a bluff that would be easily called by the EU.

All of this leads me to believe that anything - literally anything - will be said, done, threatened or promised to avoid a "Yes" vote between now and Thursday. This is a "Dunkirk moment" for the British Establishment. Everything is on the line.

By the way, the same does not apply to Northern Ireland. Even the Tories would secretly be somewhere between indifference and relief if Northern Ireland opted out of the UK

I don't buy the London line that a currency union cannot be negotiated. Scotland's currency cannot be confiscated any more than Sterling could have been removed by London as a currency from post-independence Ireland.

Like Pat Cox, I cannot see the EU cutting an independent Scotland adrift.

Nor do I take the line that independence is "irreversible"; if Scotland having voted "Yes" were to change its mind, London would welcome them back with open arms.

If the vote is "Yes", Scotland simply will have to be accommodated. Contrary assertions are crude bluffs and nothing more.

Ireland - North and South - will be affected by the outcome, either way. The entire "Ulster-Scots" politico-cultural axis would be re-defined by a "Yes" vote. The northern Unionist mind-set would be radically affected in a brave new world of a lessened UK.

Even if the vote is "No", Devo Max for Scotland would change Northern Ireland's political landscape.

And if the vote is a narrow "No", Salmond will win anyway. Independence will be on the permanent agenda politically. This week will not be pretty; but it will be riveting.

Sunday Independent