Have you organised the street party yet? Stocked up on champagne? Did you remember to book the day off work tomorrow since, shockingly, it has not been declared a public holiday? Thought not. Neither have I, to be honest.

May 1 is the 300th anniversary of the Act of Union between England and Scotland. It tells you everything that you need to appreciate about the election for the Scottish Parliament that Labour, as the Establishment in Edinburgh, has no desire to remind voters of this fact, while the Scottish National Party is more than happy to have it mentioned. If most of the opinion polls are to be believed, then Alex Salmond and his supporters are on the verge of becoming the largest single party north of the Border, with the moral right to seek to form an administration.

If the SNP triumphs, there could be a referendum on independence within three years. The impact of such a victory would be more seismic for the United Kingdom that anything that occurred in coastal Kent on Saturday morning. It may mean, at its most spectacular, that a future prime minister, Gordon Brown, may find himself, technically, a foreigner in the country over which he was ruling. It is awesome.

Yet, there are also reasons to suspect that it will not happen quite as prophesied. Having spent a few days in the Scottish capital last week, pacing the streets of two key constituencies, employing a wet finger held aloft in the air and an open pair of ears, I conclude that the result on Thursday will be less clear-cut and more complicated. If not immediately, then within months, it will become obvious that the only political combination that will work in forming a Scottish executive is the “traffic light” option – the alliance of Labour (red), the Liberal Democrats (yellow) and the Greens.

There are three reasons for claiming that this contest will be closer than advertised.

The first is that the SNP and its supposed victory has become the issue in this race. That was not so a few weeks ago when the ballot was being portrayed as a plebiscite on Labour/Blair/Iraq/cash for honours/the absence of rain to water the garden. If the SNP ultimately falls short in this epic fight, it will be because it peaked too early.

The second involves the character of the Labour effort. It is eerily similar to the Conservatives’ 1992 general election strategy. It is focused remorselessly on tax and trust. The phrases “bombshell” and “double whammy” have not actually been employed (Scottish Labour cannot afford to pay the royalties to Chris Patten) but they might as well have been conscripted. Mr Salmond is being cast as the de facto Neil Kinnock, all slick talk but not the sort of chap to whom one would allow control of a country. English voters were unwilling to admit that they shared these doubts until in the privacy of the polling station. The Scottish middle class may be much the same today.

Finally, there is the electoral system. Citizens are invited to vote for a constituency member and a party at the regional level. Despite the best attempts at public education, there remain hundreds of thousands of Scots who think that being asked for a second vote means that they are obliged to identify their second favoured party, which they are not (if strong partisans they should back their own party twice). This means that the smaller forces – especially the Greens – are about to do much better than the opinion surveys are projecting. All these possibilities may yet serve to rescue the Labour Party.

But if they do, the same wet finger indicates that Labour is poised to win the battle but has already lost the wider war to nationalism.

As a regular visitor to Glasgow and Edinburgh I am struck on every trip by the sense that Scottish identity is surging; each time I feel a tad more like a outsider. That this Kulturkampf is marching in one direction manifests itself from the ubiquitous symbols, such as the flag of St Andrew, to the minor observation that the booming high-end restaurants in Glasgow and Edinburgh are promoting themselves on the Scottishness of their ingredients and menus.

And, it has to be conceded, even by a sympathiser, that the prospectus for Unionism is uninspiring. The Scottish Conservative Party is the living dead, a body in a similar position to those, after 1945, who had been ardent collaborators in Vichy France. It is as relevant to Scotland today as 18th-century Whigs to contemporary England.

Labour is in effect the party of the Union but it is really struggling with that mantle. It can conjure up statistics in favour of the status quo, but nothing with emotional energy. It is “I speak your weight” stuff, unseductive to anyone outside accountancy. If the future is a tussle between Braveheart and the bean-counters, then it is decided.

For my overwhelming impression is that the Union has become a marriage of convenience, verging on the loveless, where the main argument against divorce is the hassle of it. While there continues to be a centre-left parliamentary majority in London, that factor will be strong enough to defer separation. Ten minutes after any future Conservative government is elected by English voters, the Scottish Labour Party (never mind the SNP) is likely to bolt for the door marked “Exit”. Many Englishmen will not be bothered by this, but I would profoundly regret it. That will not, alas, prevent it from transpiring. In the event that you have organised anything to mark the 300th anniversary of the Union, I would not rush to set up a committee to oversee a 350th birthday commemoration.

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