And so, with a single press release, the SNP have put an end to one of my theories from a few weeks ago - there is clearly now no chance whatever of a full-scale coalition with the Tories after the election in May. In one sense, to rule that possibility out so unequivocally seems a trifle rash, given that it provides the most plausible route by which the SNP might be able to remain in power if they slip to second place. It's also worth pointing out that their Welsh sister party Plaid Cymru have no such bar on coalition with the Tories, and indeed came within a whisker of forming one in 2007. So the SNP have consciously made a choice they didn't have to make - they've cut away their own safety-net, and ensured they will almost certainly have to defeat Labour outright next May to hold on to power.
It's not hard to see why they've done it, though, since the election battle will to a large extent be fought over which party can best stand up for Scotland against a Tory-led government at Westminster - hence the suggestion in the press release that it's Labour who are quietly keeping their options open and might well consider a deal with the Tories. The supporting evidence cited is that there is a Labour/Tory coalition in no fewer than five of Scotland's 32 councils, and that since 2007 Labour have voted with the Tories in the Scottish Parliament more often than the SNP. Now, in the literal sense, that's a bit thin - while Labour's irrational hatred of the SNP would probably lead them instinctively to favour coalition with the Tories if that was the only way of keeping the Nationalists out (hence what's happened in the councils), they nevertheless have a fiction of anti-Tory purity to maintain to keep their own electorate onside, and that would almost certainly preclude any chance of a formal coalition with the Tories at Holyrood. As for the parliamentary voting record, it is of course much easier for opposition parties to find common cause against something than it is for any opposition party to vote with the government in favour of a specific proposal. Such statistical analyses are therefore very crude - but Labour can hardly complain about their use in this case. They have, after all, spent much of the last decade-and-a-bit using voodoo statistics to peddle the fantasy of a de facto SNP/Tory alliance, both at Holyrood and at Westminster.