A S SCOTLAND prepares to celebrate what could be the last Hogmanay before the break up of Britain, there is an air of unreality about the independence debate.

The opinion polls have scarcely moved all year, with support for independence still stuck at around 30%. Yet, the UK cabinet, we are told, is increasingly anxious about the result of September's referendum. Coalition ministers are apparently worried that support for the union remains brittle, and vulnerable to a late surge of support for nationalism.

Questions are being raised about whether Alistair Darling, the former Labour Chancellor who chairs the Better Together campaign, is sufficiently combative against Alex Salmond. However, it's hard to believe that a more belligerent politician could have done much better. Or does David Cameron know something that we don't? Have focus groups detected an early change in the tide of opinion in Scotland?

Certainly, the big event of the year, the publication by the Scottish government of the independence white paper "Scotland's Future" in November did not appear to generate much momentum for nationalism. It was billed as the answer all the questions about independence - over six hundred of them. But critics said it answered all the questions except the ones that mattered.

Now, the white paper was, in many ways, an admirable document. It was very clearly written; it did address lots of technical questions about citizenship, passports etc; and contained a number of rather interesting policy ideas - such as the offer of universal child care, which according to reports is likely to be adopted by the UK Labour Party at the next election.

However, as always in politics, the answers you get depend on the questions you ask. There was nothing in the White Paper about what alternative currency an independent Scotland might adopt if it is either denied the use of sterling, or offered a currency union with England on unacceptable terms. The Scottish government insist that there is no prospect of Scotland not being allowed to use the pound and so the question was otiose.

Most independent commentators on the question agree that it is difficult to see how Scotland could be prevented from using a convertible currency that is used all over the world. Most agree too that it would not be in England's interest to refuse to recognise Scottish pounds - in the way London cabbies used to do - because it would damage relations with one of England's biggest trading partners.

However, the question will not go away, no matter how hard the Scottish government wishes it would. Currency has somehow lodged in voters' minds as a key one in the referendum. Whether this is the result of unionist scare-mongering, a biassed Scottish press, or a lack of confidence among Scots hardly matters. The question is there and it won't go away.

One reason, perhaps, is that when people go on holiday, the first thing they do is change currency - often getting ripped off by hidden charges. After the passport, this is the most direct experience of "abroad". Unionists have long used the spectre of border posts to dampen support for separatism. They conjure an image of nosey tartan police and customs officers at Carlisle checking passports, asking impertinent questions about how much currency you are carrying and what you have in your boot.

Now this image may be an entirely false one. As the SNP point out, there are no border posts between Northern Ireland and the Republic of Ireland. And the EU has largely done away with border posts. The reason Scots have to change currency when jetting to the Costas is because Britain has decided to opt out of the euro. But that hasn't dispelled the anxieties.

Now, in Catalonia, which is seeking a referendum on independence from Spain you don't hear much talk of currencies, EU membership, pensions or any of the issues that dominate debate here. These are be regarded as the small change of national liberation. Catalans want freedom from what they regard as oppressive rule from Madrid - to be masters of their own destiny.

The SNP would like Scots to feel the same about London rule, and believe that Scots have a legitimate grievance. Too much of the wealth of the country is syphoned off by the financial kleptocracy in the City of London. Scotland's best educated workers tend to drift south because of inadequate job opportunities here. Scottish businesses cannot get capital because it flows south.

But so far the Scots have not seen independence as the answer to these problems. And the White Paper does not appear to have persuaded many of them. Opinion polls following the publication showed a marginal increase in Yes vote support, but nothing statistically significant.

The White Paper for all its 600-odd answers has not addressed the greatest question of all: why do Scots feel so closely identified with an entity, the United Kingdom, which the Nationalists claim has stolen their oil, their best brains, their biggest companies and given little in exchange other than the Barnett Formula and nuclear weapons on the Clyde? What is it that binds Scots to the union?

The answer is of course history. The three centuries in which Scots mostly regarded themselves as partners, albeit junior partners, in a common project: Great Britain. It is the legacy of an Empire, long gone, in which Glasgow regarded itself as "the Second City", and Scottish soldiers fought as redcoats across the world. Scots have really only started thinking of independence as a practical possibility in the last decade or so - since the creation of the Scottish parliament. It seems unlikely that this weight of history can be dispelled in the nine short months left until the referendum in September.

However, it is not impossible. After all, the Scottish voters have certainly shown that they are capable of voting in very large numbers for the party of independence, the SNP. In 2011, the Nationalists were trailing Labour by ten points in the polls at this stage in the Holyrood elections, and yet Alex Salmond went on to win by a landslide.

This is what is giving civil servants in Westminster sleepless nights. Is it possible that the debate about the currency has largely been taking place in an echo chamber created by the Scottish media? It may be that the debate seems artificial because the Scottish people haven't started thinking seriously about their voting intentions. Once they consider the options, and the possible consequences of a No vote, they may surprise us all. It seems a long shot - but then Alex Salmond, the great gambler of Scottish politics - has already placed his bet. And he doesn't like to lose.