05/05/2015 11:09 BST | Updated 01/05/2016 06:12 BST

There Are Many Reasons Why Scotland Is Being Bowled Over by the SNP - and the Other Parties Can't Overcome Those by May 7th

It wasn't supposed to be like this. At least that is the view of Scotland's Unionist parties. Because despite losing last September's referendum on independence by a decent margin the Scottish National Party now appear on course for a landslide victory at next week's general election.

It wasn't supposed to be like this. At least that is the view of Scotland's Unionist parties. Because despite losing last September's referendum on independence by a decent margin the Scottish National Party now appear on course for a landslide victory at next week's general election. If polls are correct then the party is set to increase its representation in the House of Commons from six seats to perhaps as many as 50, almost wiping out the Liberal Democrat presence in Scotland and blowing a near fatal blow to the Scottish Labour party. It would be one of the most remarkable outcomes in recent British election history. The SNP may win convincingly even in stalwart Labour areas of the central belt, overcoming huge majorities and brushing aside long-serving Parliamentarians in the process.

How to account for such a swing towards the Scottish nationalists? Firstly, during the referendum the SNP organised itself into an effective and ruthless campaigning machine. And since September its membership has shot up from 22,000 to nearly 100,000, making it the UK's third biggest political party by membership. This army of new recruits have been pounding the streets of Scotland, enthused by the sense of purpose and belonging that many found in the pro-independence campaign, and spreading a compelling message that only Nicola Sturgeon's SNP can stand up to a stale Westminster system and deliver more a more progressive, equal society for Scotland.

The timing of the election itself benefits the SNP. A large number of people have channeled their frustration of losing the independence vote into support for the SNP. Were votes being cast six hence then "referendum fever" might have dissipated enough for Yes voters to have drifted back to other parties. This is magnified further in the nationalist's favour because SNP voters are more likely to turn up at the polling booth than those who have decided to stick with Labour or the Lib Dem.

But there will also be many next week will be voting SNP for the first time, believing that plumping for them is now risk free. Whilst a vote for the SNP previously has always carried the tacit risk that one might be voting for independence, at this election the issue is off the agenda. Voters who sympathise with the SNP's broader political agenda may now be more inclined to lend it support. And Ms Sturgeon will benefit from a broader change in voter behaviour. Scots used to vote Labour at national elections, opting to send SNP candidates only to the Edinburgh Parliament. But now they are being swayed by promises that SNP MPs, not Labour ones, will stand up for Scotland in Westminster.

The SNP rides high in public opinion because there is widespread belief that it delivers for Scotland and can be trusted to continue doing so. The party had administered the devolved Scottish government since 2007 and their approval ratings remain strong. Partly these ratings reflect widespread public confusion over who does what in Scotland. Parliamentary candidates from the London-based parties are constantly blamed on the doorstep for failings on policies that actually full in the purview of SNP politicians in Holyrood. Ms Sturgeon and her predecessor, Alex Salmond, have only been too happy to project a view that the bad things that befall Scots have been the result of UK government cuts or Westminster meddling, whilst anything good that happens is directly linked to the decisions of benevolent SNP ministers.

Lamentably this narrative has remained unchecked by the opposition in Edinburgh, much of the Scottish media, and indeed by successive governments in London. The latter should also have done more, had it not been for an unfounded fear of stoking nationalist sentiment, to remind Scots that they too governed on their behalf. Greater understanding of the Scottish devolution settlement (something that Westminster parties now admit they should have pushed) and where actual responsibility lies might have led to greater public scrutiny of SNP performance in areas like housing, healthcare, and education (where they have been guilty of failings).

Many of the SNP's new found supporters are defectors from the Liberal Democrats, who are suffering a UK wide backlash following their decision to enter into a coalition with the Conservatives. The majority will have come from the Labour party, which has suffered a brisk and unsightly collapse since the referendum. Labour is charged with taking its support base in Scotland for granted. When, after the referendum, party leaders complained that "Scotland has deserted Labour" Scots rightly suggested that Labour was in fact guilty of "deserting Scotland". Many also can't forgive Labour for "climbing into bed" with the Conservative party during the referendum campaign. It is an understandable grievance, although it would have been difficult for Labour to have avoided joining the multi-party "Better Together" campaign and still ensure the safety of the Union. Scottish Labour MPs are talking up their chances next week, but in reality few are particularly optimistic about holding their seats. Perhaps the decision by a number of Labour and Liberal stalwarts to stand down from their seats this time around was prompted by a desire to bow out gracefully rather than suffer ignominious defeat at the hands of the nationalists.

Winning close to 50 seats will be tougher for the SNP than polling might make one think. UK election polling always contains a margin of error. National polls do not take into account local complexities, of which there are many, nor voter loyalty to decent incumbents. SNP voters have been far more likely to give away their voting intentions than "shyer" supporters of other parties. And polls out in the last few days which suggest an SNP whitewash might have the effect of "shocking" anti-SNP voters who might otherwise have stayed at home into making the journey to the polling booth. In a similar way, polling late in the referendum campaign which showed the Yes campaign in the lead are credited with cementing the No vote.

And recently the Westminster parties have started to up their games a little and mount a more determined challenge to the nationalists. The Lib Dem leadership is putting all of its efforts into defending its 11 Scottish seats rather than attempting to make gains elsewhere. Alex Salmond, originally thought a shoo-in for the Lib-Dem held seat of Gordon, has apparently been worried enough about the possibility of not winning there that he cancelled a book tour of the US in order to show his face in the constituency. Jim Murphy, the energetic new leader of Labour in Scotland, has made efforts to rejuvenate his party, and he may have succeeded in stemming a hemorrhaging of support. But he does not seem to have closed the gap with the SNP. Labour activists seem more concerned with next year's Scottish parliament elections than defending their vote share this May.

The Scottish Conservatives are fighting a vigorous campaign, and in the Scottish borders, where Tory support is strongest, they have a chance of adding to their sole Scottish seat. It is one of the great fictions of Scottish politics that Scotland doesn't vote Tory (the other is that Scots are far more "progressive" than the English; there are grains of truth to both myths, although they are over exaggerated). It does, although to be sure not in massive numbers. At the 2010 general election the Tories got just 3% less of the vote share than the SNP. Its votes are spread out in such a way that they do not turn into seats. But they came a strong second in a number of constituencies last time, and if Labour and the SNP split the left wing vote in one or two of these the Tories might just limp over the finishing line.

Reports in recent months that a number of pro-Union organisations are encouraging tactical voting in order to defeat the SNP may be a little exaggerated. But the issue of tactical voting is certainly at the fore in Scotland and some candidates are putting it at the centre of their campaign strategies. The Lib Dems even publicly admit to it. The Westminster parties have a duel challenge on the doorstep. One, to shore up their own support and make sure it delivers, but secondly to persuade others to ditch parties with little chance of winning and cast an "anti-SNP" vote for them instead. Some candidates are asking voters to decide who they dislike the least: "me, or the SNP guy?"

Miserably for the Pro-UK Westminster parties they are ultimately doing too little, too late. The question for the evening of May 7th is not whether the SNP will become Scotland's largest party, but to what degree. In just a matter of days a party with the stated aim of breaking up Britain will become the third largest force in the UK parliament. This prospect is rattling the cages of Westminster politicians, especially in the Conservative party, who have made the SNP and a potential relationship with Labour a campaign issue in itself.

Ms Sturgeon says that a large showing of nationalist MPs in Westminster would rock the establishment and make sure that Scotland's voice gets heard in London. Her manifesto promises that the SNP would force the next UK government to give ground on a number of nationalist demands, such as the cancellation of Trident renewal, the ending of austerity, and the granting of "full fiscal responsibility" to the Edinburgh parliament.

But the great irony of a large SNP contingent in Westminster is that Scots will actually have less influence at Westminster. Scottish voters will be consigning their countrymen and women to perpetual political opposition, rather than to the front benches of government where they have disproportionately dominated in recent British administrations. The result is that UK governments will become more England focused and Scotland may find herself squeezed out. Perhaps that is what the SNP, seeking the eventual removal of Scotland from the Westminster system, really wants.