In 2007, the Scottish National Party (SNP) topped the poll at the Scottish Parliamentary Election with 32% compared to Scottish Labour's showing of 31%. Only 1 seat separated them in the ensuing parliament (47 to 46) and the SNP governed as a minority administration until 2011.
By the time a new parliament met four years later, the SNP reigned supreme. They were returned to government with a resounding 45% of the vote and an absolute majority of 69 seats. Labour, though reduced to 37 seats, garnered 29% of the vote. Labour's greatest defeat was the rout they suffered in constituencies across the Central Belt.
A few years passed and, in 2014, 45% of the Scottish electorate voted for independence. Fast forward to May 2015 and many pollsters are predicting a SNP landslide north of the Border with estimates of their likely take of seats ranging from 30 (a bit low) to over 50 (a tad optimistic). The question on most people's lips is: why? Why, with 55% of Scots voting to remain in the Union, are the SNP on course to win such a large share of Scottish seats? Why, despite eight years in government, are the SNP not suffering mid-term blues? Why, for that matter, are some people in England Googling whether they can vote for the SNP too? Let's take in each in turn.
Firstly, the 55% of Scots that voted to remain in the Union were mostly drawn from the three Unionist parties - Labour, the Conservatives and the Liberal Democrats. Having done what many people say that they want political parties to do - working together on issues they agree on - these three parties went on their separate ways as soon as the polls closed (arguably this happened earlier).
On the flip side, the 45% of voters that backed independence identify their cause as best served by the only major party advocating it - the SNP. Unionism is a divided creed, if a creed at all, whereas the SNP are the best hope of achieving independence. If one party came to represent the Union, as the Unionist Party did until 1965, it may well enjoy support to eclipse the SNP. Conversely, were a new Scottish independence party with a different (centre-right) social agenda to be born, it could sap the support currently funnelling to the SNP.
Secondly, it is interesting that despite the SNP governing Scotland for almost eight years, voters show no sign of the mid-term fatigue one would usually expect. This likely stems from the 'outsider' position the SNP have been keen to stake out for themselves, and to retain as long as possible. Combine a Conservative/Liberal Democrat coalition government in office since 2010 with a Scottish Parliament that, until the 'Vow' is honoured, lacks meaningful financial powers means the SNP have been very successful at attributing unpopular policies to Westminster and popular ones to themselves. You might have noted that during the UK Leaders' Debate Scotland's First Minister Nicola Sturgeon mentioned one policy the SNP are using to help young people onto the housing ladder - Help to Buy. She did not credit Westminster for the policy.
There is also the not insignificant matter of the SNP's record in government. Rightly or wrongly, most Scottish people think they have done rather well. They certainly regard the record of the SNP far more favourably than either the current Westminster government or the previous Labour/Liberal Democrat coalitions in Holyrood.
Lastly, Nicola Sturgeon's SNP are a new voice on the UK political stage to many people. They are stridently anti-austerity, unilateralist and remarkably honest about their intentions for the next parliament. In other words, the SNP act and talk differently to most political parties. No wonder some English people are crying out for an alternative despite the obvious ridiculousness of the proposition.