POLITICIANS often say more than they mean to say. Yesterday, in her post-election address to the Scottish Parliament, Nicola Sturgeon invoked the spirit of 1992. She said there was then a “coming together” of parties to campaign for a Scottish parliament under the shadow of Tory rule. That was via the cross-party Scottish Constitutional Convention.

This was puzzling, not least because the SNP boycotted the Constitutional Convention back in the day. Nationalists said the Labour-led campaign for a Scottish parliament was a “Unionist trap”. In 1992, the SNP was a marginal force, and won only three seats in that year’s General Election. Labour returned 49 MPs. Perhaps she mentioned 1992 just to rub salt in their wounds.

But it may also have been a subliminal recognition that, despite the SNP’s electoral success last week, an era has come to an end – an era that began in the early 1990s when the SNP adopted the policy of Independence in Europe. For next month, the SNP is going to have to start remaking the case for independence, at least for a time, outside Europe – the Scottish equivalent of a hard Brexit.

In 1992, the SNP had only recently adopted this transformative policy. Alex Salmond realised that Europe was an opportunity to change the SNP’s image and make independence seem like joining the future rather than harking back to the past.

Until Mr Salmond became leader in 1990, the SNP had been, for most of its history, a romantic nationalist fringe party. The SNP opposed the EEC because it wanted true self-government. Why would Scotland want to be free of Westminster rule only to submit to rule from Brussels? (Whisper it, but probably around 25 per cent of SNP members still think this).

However, the electoral appeal of Independence in Europe was unanswerable and the new policy was hugely successful. The SNP could not have become the dominant political force it is today without the policy of Independence in Europe.

No longer could the party be accused of “separatism”. Instead of breaking away, and becoming a wee isolated tartan statelet, independence meant joining something bigger: Europe. The SNP could claim to be internationalists and more enlightened than the “Little Englanders” who opposed Europe.

Independence in Europe solved a whole raft of “disengagement” problems. Since the whole of Britain would be in the European single market, there need be no regulatory or customs divergence between Scotland and England after independence. Friction-free trade was built in. A borderless nationalism ceased to be an oxymoron and became a practical reality.

Nationalists in the 1990s believed, with good cause, that further European integration was inevitable. That matters like overall economic and monetary policy, and even defence and foreign affairs, would increasingly be decided at a European level. No one seriously believed that Britain would ever leave the EU. Not even the English could be that stupid...

Independence became a kind of federalism – not just in a European context, but in a British one as well. Scotland could become independent and still be part of the UK. The 2013 independence White Paper, was essentially a confederal project, with Scotland in a monetary union with the UK.

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It didn’t even mention the trade or regulatory issues that have dogged Brexit, because both England and Scotland would be in the EU single market and the customs union. Immigration was no longer an issue because of free movement. Environmental and agricultural policies were all governed ultimately by Europe. Better Together scares about border posts could be laughed off.

Not any more. Brexit has made independence in Europe untenable because Scotland will be out of it before self-government happens. The SNP will have to go back to arguing a much harder case for national sovereignty, without the continuity membership provided by common membership of Europe. Hard border at Gretna. A national hard currency. An independent trade policy. Customs duties.

Of course, Brussels will make it as easy as it can for Scotland to rejoin the EU, but that will be much harder in future precisely because the rest of the UK is not part of it. Moreover, it cannot be assumed, just because MEPs have been expressing support for independence during Brexit, that the EU will do so after the UK leaves. Brussels is intensely hostile to secessionist movements. Note how it has tolerated appalling violations of human rights in Catalonia. It cannot be seen to be encouraging secession, even in non-EU countries.

Moreover, post-Brexit Europe will likely become more deeply integrated and federal, especially over monetary and fiscal policy. Brexit has shown that giving opt-outs to countries like Britain only makes matters worse. An independent Scotland will lose those opt-outs and will have to sign up, formally at least, to the euro as part of the Maastricht Treaty.

Unionists will point out that the vast majority of Scottish exports go south, not east. For the first time since the 1990s, the SNP will have to make the argument for Scotland having a different trade policy, on customs and regulations, from that of its largest trading partner: the UK.

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None of these problems is insurmountable. Indeed they are minor details for people whose over-arching ambition is to depart from Westminster rule. When Eastern European countries became independent in the 1990s, currency was never an issue.The SNP can still argue for independence in Europe – but it becomes an aspiration, not a recognition of a current reality.

But it will matter to the many fair-weather nationalists who saw the 2013 offering as too good to miss. Federalism looks safer. Also, the SNP’s Brexit supporters, like the former minister, Alex Neil, will say that Scotland should have a referendum on EU (re)membership, as used to be party policy.

Now, it may be that Scots have already made their choice, and that independence is the “settled will” of the people, much as Labour said devolution was, back in 1992. But the SNP must face up to the reality that the very meaning of independence is changed post-Brexit.

It goes against all her instincts, but must after years arguing against a hard Brexit, Nicola Sturgeon will have to start making the case for what Unionists will inevitably call a “hard Scexit”