As regular readers know, I think one of the very few potential clouds on the horizon for the SNP at the moment is the Swinson Factor. We know from past history that London parties often fare better in Scotland when they're led by a Scottish MP, and indeed there's already evidence in a new YouGov poll that Jo Swinson may be more popular in Scotland than elsewhere in the UK - or perhaps a more accurate way of putting it is that she's less unpopular here than elsewhere. Across Britain she's rated favourably by 26% of respondents and unfavourably by 38%, whereas in the Scottish subsample it's a tie of 29% apiece. Scotland is the only part of Britain where she's not firmly in negative territory.
And yet so far there's no sign of the SNP taking a hit. That might yet happen if there's some sort of Cleggasm-style bandwagon effect during the election campaign, but on the other hand it might not. I have a sneaking suspicion that what might insulate the SNP from the Swinson Factor is what is sometimes called "the Ulsterisation of Scottish politics" - a term that, according to a recent article by Stephen Daisley, was coined by his one-time protégé Aidan Kerr. That's a richly ironic origin, given that few people have done more to entrench the Ulsterisation than Kerr himself during his time as a Scottish Labour propagandist. In the overall scheme of things, it's not that long ago that people who were sympathetic to Scottish independence saw no contradiction in voting Labour or Liberal Democrat, but those days are well and truly over thanks to the near-sectarian attitude of the likes of Kerr.
The way that Ulster politics works is that unionist voters almost always vote for unionist parties, regardless of whether there's a politician or policy they like on the nationalist side of the divide. And, of course, vice versa - nationalists don't vote for unionist parties. By taking such an extreme stance on an independence referendum (ie. that they will block it even if there's a clear mandate for it), the Lib Dems may have disqualified themselves in the minds of Yes voters as thoroughly as the DUP have disqualified themselves in the minds of Irish nationalist voters. Which means that any extra votes that the Lib Dems take in Scotland thanks to the Swinson Factor may well come disproportionately from other unionist parties - and under a first-past-the-post voting system the main beneficiaries of that would, ironically, be the SNP. Most seats are either SNP-Labour or SNP-Tory battles, and if the Lib Dems start taking votes away from Labour and the Tories in those seats, it's bound to make it somewhat easier for the SNP to win.