YESPRIDEPleasing as it is to see last night’s vote in favour of equal marriage at Westminster, and to know that the Scottish Government’s parallel process will surely bring fruit, the SNP’s Westminster group’s decision not to vote still perplexes me. Kate’s got a fantastic post up about the implications of the Westminster proposals for Scots law, the roll-call of shame, and concerns about the SNP’s reasoning: I agree with all of that, and there’s no point replicating her arguments here.

There are other concerns, though, about the SNP abstention. The UK is, unless and until the referendum is won, a single nation-state. Until that point it’s extremely hard to identify what does not affect Scotland, and the question of whether England and Wales deliver marriage equality certainly does matter to Scots.

People live, work and love across the border largely without thinking about it. If two Coldstream residents want to marry in Berwick-upon-Tweed, should SNP MPs not speak up for their right to do so irrespective of gender? What if one partner is from Gretna and the other from Carlisle? If the vote had been narrowly lost last night, the effect of the SNP group’s decision would have been to tell that couple they could only tie the knot in Gretna, an idea which admittedly has some historic resonance.

So what if English MPs can’t vote on the equivalent Scottish proposals? It’s not the SNP’s fault that we have this halfway house which institutionalises the West Lothian Question. Equality isn’t a dull managerial England-and-Wales-only issue of the sort Scots MPs might well be justified in avoiding. It’s a question entirely of principle. As such, a supportive position from the SNP would have helped to offset the reputational downside for Scotland of hearing Labour’s west coast dinosaurs braying in their swamp of pseudo-religious bigotry.

Getting a vote on affairs in the rest of the UK is one of the few compensations for the Union. Until independence, if you have a vote, it should be used wherever there’s a point of serious principle at stake. Independence offers a trade-off I’ll be glad to take: losing the influence Scots MPs have at Westminster will be more than outweighed by shedding the influence Westminster has on Scotland.

SNP MPs voted against the Coalition’s hike in tuition fees: good. Scots students wishing to get an education in England and Wales would have been righteously angry had they not. But when the Coalition’s assault on the English and Welsh NHS came forward they sat on their hands. When those students get to university, or indeed any other Scot moves down south, do the SNP not wish them to have a decent NHS to rely upon? Is a publicly-run free universal healthcare system a point of principle or not?

Like it or not, SNP votes at Westminster matter. They may sometimes be decisive, but what’s more, when they’re not, they will be read as a statement of the Scottish Government’s intentions and position. Last night was a missed opportunity to be consistent and to support the idea that the principle of equality knows no borders, just as love does not.