When the SNP lost 19 of their 54 seats at the 2017 election, one of the saving graces was that it seemed logical they would exercise far more influence with 35 seats in a hung parliament than they had done with 54 seats in a parliament with a Tory majority. They were still comfortably the third largest party, and we imagined Theresa May and the Tory media sweating over which way they would vote in each close division. But it hasn't really worked out that way, partly because the Tory-DUP alliance has often shut them out, and partly because May is so intransigent on the subject of Scotland that there hasn't been any scope for bargaining - not even the whiff of an offer of a Section 30 order in return for SNP support on the meaningful votes, for instance. So that's left the SNP taking an all-out opposition posture, which means they've been on the losing side most of the time - and even when they've been on the winning side nobody has credited them with swinging the balance, because their votes were just taken as read.
But the indicative votes tonight were a very different story. The SNP had a genuine dilemma over how to vote on some of the motions (the ones that proposed different types of soft Brexit), and the decision they reached actually did determine the final outcome. If they had voted for Kenneth Clarke's proposal for a customs union, that would have been the only option that secured a majority. As it was they abstained, and the customs union idea was defeated along with the other seven motions. So at last, after two years, here it is: the SNP taking advantage of a hung parliament to influence the destiny of the United Kingdom.
Kenny "Devo or Death" Farquharson is spitting synthetic fury about the way they jumped, but it makes perfect logical sense - if your objective is to remain in the EU, you have to try to prevent any proposition that falls well short of that from emerging as the most likely consensus. (And as it happens, the Independent Group seem to have reached exactly the same conclusion - they actively voted against the Clarke motion.) Even if the SNP now downgrade their objective to their previous preferred compromise of single market and customs union membership, it would still be logical not to vote for any option mentioning a customs union only, because doing so would increase the chances of parliament coalescing around a compromise that does not involve single market membership, and that would therefore be wholly inadequate. And in respect of the ultimate goal of independence, it would from a tactical point of view be nonsensical to champion a compromise that you don't think is remotely good enough, if the first thing that will be said to you after it's delivered is: "What are you complaining about? We've given you exactly what you asked for. You don't need an independence referendum now."
So a job well done - the SNP have demonstrated to the Westminster village that their voting power does pack a punch after all, and they've done so in a way that is consistent with their strategic aims.