NEGOTIATORS call it the big gun. The bottom line. If debate is exhausted, if all our alternatives have been canvassed, considered, debated and rejected, what do you do? On Friday morning, on the steps of Bute House, Nicola Sturgeon stated her mission: to take “all possible steps and explore all options to give effect to how people in Scotland voted, to secure our continuing place in the EU.” The First Minister has a range of alternatives before her, some promising, others less so, short of pulling the trigger on a second independence referendum. Each of these must be explored and exhausted, but few of them look like flying.

Some folk hold out the hope of a solution to reflect Scottish European ambitions, inspired by Greenland’s relationship with Denmark. Along with the Faroe Islands, the autonomous island nation is part of Kingdom of Denmark.

But while the mother country participates fully in the European Union, Greenland sits outside of its relationships, based on a common market, and the free movement of goods, capital and persons. Couldn’t we knock the Danish situation on its head? Couldn’t England and Wales crash out of the European Union, leaving Scotland, fully participating in its common market?

The augurs aren’t good. Firstly, the EU is an international organisation formed by its member states, and until it is independent, Scotland remains a stateless nation. The Greenland wheeze would rely on the UK remaining an EU member state, advocating our interests, on behalf of five million Scots out of a British population of more than sixty million. This is not viable. And if you seriously believe that a UK Government – sternly instructed to Brexit by the people of England – would remain even paper members of the EU for our sake, you’ll believe anything. With the best will in the world, it cannot and will not happen.

So perhaps the First Minister might try a solution, rooted in domestic law. On social media over the weekend, a number of excitable tweeters raised the idea that Holyrood might “veto” Brexit. If only it was so simple. Under the Scotland Act, Holyrood must abide by EU law, respecting the rules of the single market. If MSPs violate EU law, their legislation can be flattened by the courts. If Westminster wants to strip these requirements out of the devolution settlement, in principle, they would need Holyrood’s consent. The same goes for any attempt to fiddle with key EU powers which the devolution legislation broadly devolves – agriculture, fishing, the environment.

And MSPs may well decline to extend their consent to these interferences. They have done so in the past, returning Iain Duncan Smith’s welfare reform to Westminster, with an instruction to abandon the parts of it extending to Scotland. In those meeker political times, the former work and pensions secretary capitulated, deleting the offending sections of his Bill. But as spittle-flecked Brexiteers never cease of reminding us, Westminster remains sovereign in the British political system. Power devolved is power retained. The First Minister may ask MSPs to refuse to give effect to the wishes of Boris Johnson and his colleagues. This may delay Brexit. It may make it more politically difficult. It may ramp up the ongoing tensions between the focussed, prepared government in Edinburgh, and the unfocussed, clueless omnishambles which currently rules in Whitehall. But this is not a veto. Or at least, not a veto with legal and political teeth. A Brexit majority in the UK parliament retains the legal power to any ignore any and every Scottish objection, ramming the changes through. Without independence, legally, we remain subject to the increasingly capricious whims of the Westminster majority, reliant on their goodwill. As the referendum result last week told us, this is now in short – very short – supply.

The ultimate lesson? There is only one reliable way for Scotland to “take back control” over our European relations. We won’t find it in the precincts of the Palace of Westminster.