Alex Massie: Alex Salmond's astute pitch to the divided playing field IN THE aftermath of Richard Nixon's landslide victory over George McGovern in the 1972 presidential election, the legendary New Yorker film critic Pauline Kael wondered how such a result was possible. "I live in a rather special world," she observed. I only know one person who voted for Nixon. Where they are I don't know. They're outside my ken. But sometimes when I'm in a theatre, I can feel them. There are pockets of Unionist Scotland in which the SNP's stunning triumph last year was met with similar bewilderment. How could this have happened? Weren't the SNP supposed to be some kind of fringe enthusiasm? Who voted for these guys? The "establishment" was caught off-guard, oblivious to and out of touch with a changed Scotland. What was once deemed impossible - independence - suddenly seemed feasible, even plausible. Next month's council elections seem likely to show the SNP's triumph was not a one-off. In contrast to Labour's rusting electoral machine, the SNP's is slick, well-oiled and professional. Winning control of Glasgow City Council would be a considerable achievement in itself but the symbolism of toppling Labour in George Square would dwarf even the practical implications of such a revolution. To adapt Benjamin Disraeli's famous aphorism, the Scottish National Party is nothing if not a national party. There are many Scotlands and the SNP must play to win in all of them. If this means the party must, on occasion, contradict itself then Alex Salmond, like Walt Whitman, responds "Very well then, I contradict myself; I am large - I contain multitudes." Recent American elections have demonstrated how political allegiances can be usefully, if necessarily generally, predicted by demographics and socio-economic status. The 2008 Democratic primary contest between Barack Obama and Hillary Clinton was, in part, labelled a "wine-track vs beer truck" battle. States with wealthy, educated, "wine-drinking" populations were likely to vote for Obama; by contrast Clinton enjoyed an advantage in states with, in relative terms, a greater number of blue-collar, white working-class, "beer-drinking" Democrats. Adapting this to a Scottish context, two SNP approaches have helped the party attain its present supremacy. They can be labelled the Hampden and Murrayfield strategies. They are different but complementary, designed to appeal to different branches of the electorate. The Hampden strategy appeals to working-class and lower-to-middle-class voters. It is populist, Saltire-wrapped and keenly, proudly Scottish. The Murrayfield tranche of the electorate is older, wealthier and more likely to consider itself Scottish and British. Though outnumbered by the Hampden vote, its influence - especially in business and the media - is disproportionately powerful. The Hampden voter, to put it crudely, reads tabloids and is, comparatively speaking, more likely to work in the public sector; the Murrayfield voter reads broadsheets and works in the private sector. The SNP message changes according to the audience. At the risk of over-simplifying matters, the Hampden voter is more likely to follow his heart; the Murrayfield voter is, in relative terms, more likely to vote with his head. For instance, the manufactured rumpus over last week's Economist cover illustration was designed to stir up the Hampden vote. How dare these Englishmen insult Scotland! Who do they think they are? By contrast, the SNP's willingness to reconsider its defence policy and at least countenance the possibility of an independent Scotland joining Nato should be seen as an attempt to appeal to a Murrayfield constituency troubled by the fine detail of life in post-independent Scotland. Similarly, the First Minister's arguments change according to his audience. When he suggests the SNP is the guardian of "progressive" values he is talking to a fiercely anti-Tory Hampden audience. When he stresses the importance of low rates of corporation tax and fostering an enterprise-friendly culture he addresses concerns more likely, relatively speaking, to be held at Murrayfield. Polling shows that Hampden and Murrayfield live in different Scotlands. In February, Ipsos-Mori found that while 51 per cent of voters in the least affluent parts of Scotland support independence, just 26 per cent of those in the wealthiest 40 per cent of areas do. Though pollsters" margin for error increases in these sub-samples, the disparity between these numbers remains stark and striking. These results confirm both the success and the limitations of the SNP's "Standing Up for Scotland" campaign and its determination to resist cuts in public spending. The Hampden voter is reassured by this; the Murrayfield voter is likely to wonder if such largesse would be affordable in an independent Scotland. Nevertheless, it seems likely the SNP is closer to its "ceiling" at Hampden than at Murrayfield. To some extent, future growth for the independence cause requires the party to do more to appeal to wealthier, older voters. No wonder the SNP switches gears. One moment it heralds the great advantages that will come with independence; the next it reassures anxious voters that many things will not change at all. Increasingly Salmond reverses Lampedusa's oft-quoted adage that "If we want things to stay as they are, things will have to change." On the contrary, the First Minister suggests, if we want everything to change, many things must stay the same. This is the heart of his case for an enduring Social Union between the peoples of these islands. Inevitably, many of the defining totems of "British" culture will endure even after independence. This is realistic, and cunning. It tells voters they express their Scottishness at the ballot box without forfeiting many of the things that contribute to their parallel, if sometimes unacknowledged, Britishness. You can be Scottish and British and vote for the SNP. Doubtless Salmond's opponents consider this proof of his incurable slipperiness but it is fairer to view this strategy as an attempt to assuage reasonable concerns. The First Minister offers pride and reassurance as he seeks to forge an electoral alliance uniting Hampden and Murrayfield. No wonder some Unionists still seem bewildered.  Alex Massie will be online at 11am today to discuss this column. Join him at www.scotlandonsunday.com/opinion