Michael Fallon, who was probably just shooting his mouth off without his masters' knowledge, has walked back his "forget it" comment about Indyref 2 at a rate of knots. But this may be a useful moment to remind ourselves that, whatever they may choose to believe, the UK government are not actually in a position to use Spanish-style autocratic powers to close down the issue of independence. If by any chance they do try to block a binding independence referendum, the SNP would have four clear options, none of which London would realistically be able to interfere with.
1) A consultative referendum could be called. This might end up in the courts, but Professor Robert Black believes such a vote would be legal as long as the question is chosen with care (ie. 'Should Scotland be an independent country?' wouldn't be an option).
2) A snap Holyrood election could be called, and could function as a de facto consultative referendum, with the pro-independence parties making clear in their manifestos that they would regard a parliamentary majority as an outright mandate for independence, without any further need for a referendum. (Technically Nicola Sturgeon doesn't have the power to call an early election, but under the rules it would be easy enough to bring one about.)
3) As the Tories are raising hair-splitting objections to the quality of the mandate for a second indyref, the SNP could call their bluff by using a snap election to obtain a mandate for a specific pledge to hold a referendum in 2018. "What's your excuse now?" they could then ask.
4) The SNP could withdraw from Westminster. The almost total absence of Scottish representatives from the UK's only national democratic institution would not be sustainable in the long-run, and would bring matters to a head sooner or later. This is probably the least likely of the four options, because it would carry the significant risk of the SNP being regarded as having let their own constituents down. But it's a perfectly viable (and legal) option if all else fails.
This is the moment when someone pipes up and says "you're forgetting option 5 - UDI". But let's be serious - in the modern world, you can't declare independence without a specific mandate.
* * *