Leader: Nothing can be ruled out but Scots coalition remains unlikely

Coalition politics may have made a historic breakthrough at Westminster, but could an equally convention-shattering coalition be in prospect in Scotland - with a tie-up between Labour and the SNP?

The deep philosophical divide between the two parties - and the ferocity with which they have fought each other in recent years - would suggest that such speculation is the product of a most fevered imagination.

But with the party conference season approaching - and the clock counting down for the Scottish parliamentary elections in May - fevered imagination is in overdrive. Former Liberal Democrat leader Charles Kennedy moved to deny strongly speculation over the weekend that he may be considering defection to Labour - a suggestion with which Labour leader contender Ed Miliband made mischievous play in a leadership hustings in Edinburgh.

Might there not be a Scottish Lib-Dem-Labour coalition? Or a Conservative-SNP-Lib Dem pact to keep Labour out of office? In politics, nothing can be ruled out. This is particularly so in such febrile times, with the Conservative-Liberal Democrat coalition facing unpopular decisions in the looming Comprehensive Spending Review and the opposition parties set to make the most of this discomfort. In Scotland Labour and the SNP have been vying to secure the public sector vote and have been making broadly similar noises against the deficit reduction programme.

But for a Labour-SNP coalition to be taken seriously, several unlikely developments have to unfold. Alex Salmond would need to quit as SNP leader. The 'fundamentalist' wing of the SNP - a large and vociferous number of supporters and party workers - would need to roll over and lie doggo. And within both parties there would need to be sufficient agreement on a range of issues to sustain such a coalition in office and support for Iain Gray as First Minister. Who knows what might happen in what the speculation describes as a "post Alex Salmond era". But for the moment all this seems as likely as a squadron of pigs in a fly-past over Holyrood.

Sources described as "close to Mr Gray" say the Scottish Labour leader has taken the mooted approach as a sign that senior figures in the SNP are preparing for defeat at the next election. Certainly the SNP's performance in the May election was a big disappointment for the party. And the continuing controversy over the compassionate release of the Libyan bomber al-Megrahi may take a significant toll. But the latest opinion poll findings suggest that, far from there being a collapse in support for the SNP, it is regaining ground.

Two polls conducted in the last week - one by YouGov for the SNP and the other by IPSOS MORI - put the party neck and neck with Labour. If these poll indications are sustained, talk of the SNP throwing in the sponge and doing a deal with Labour seems most unlikely but the climate could scarcely be better for the speculators.