SCOTLAND United was the name given to the radical home rule initiative in the early 1990s that brought together Labour supporters and independence supporters in a righteous coalition against Thatcherite Conservatism. Many still recall the late William McIlvanney telling some 30,000 people gathered in Edinburgh during the 1992 European Summit: “We gather here like refugees in the capital of our own country.”

Those words came winging back to me last week as Scotland united once again in face of a UK Tory Government that is now speaking the language of the European far right, and seems determined to turn EU workers into second-class citizens – refugees in their own Europe. The proposal by the Conservative Home Secretary, Amber Rudd, that migrant workers should be placed on a register, and firms named and shamed for employing them, has sparked a deep sense of moral outrage in Scotland and across Europe.

The Scottish political tribes put aside their constitutional squabbles for a moment and found a common voice. The First Minister, Nicola Sturgeon, used an article in the Labour-supporting Daily Record to condemn “thinly-veiled xenophobia” at the Conservative conference, and the misuse of EU nationals living in Britain as “negotiating cards”, as the Trade Secretary, Liam Fox, described them. Economic hostages in the Brexiteers’ battle of Little Britain.

The liberal-minded Scottish Tory leader, Ruth Davidson – the Tory right's human shield north of the Border – claimed last week that the Scottish National Party “did not speak for Scotland”. But the First Minister clearly did speak for a large part of it last week. Even the Daily Telegraph's self-styled “black-hearted unionist” Alan Cochrane condemned Amber Rudd's proposal as “stupid and inflammatory”. The Daily Record editorial summed it up ruefully: “Even those who instinctively feel we are “better together” will start to consider that independence is the only way to save ourselves from an increasingly bitter political mood in England”.

The sight of Ukip MSPs reportedly engaging in a scuffle in the European Parliament seemed somehow in tune with the bitter times. It was reminiscent of those clips you used to see on YouTube of rightwing politicians in former communist countries coming to blows in TV studios. Is this what British politics has become? Even Tory commentators agree that the turmoil in Nigel Farage’s party is because Theresa May has stolen his populist clothes. The Conservative Party is becoming indistinguishable from Ukip.

Meanwhile, the German Chancellor, Angela Merkel, was applauded by German business leaders for a speech calling on the EU to unite in resistance to British Brexiteers trying to gain access to the European single market without accepting free movement. The French President Francois Hollande went further. “There must be a threat, there must be a risk, there must be a price” for Britain's actions, he said. Normally, we would condemn such undiplomatic language, but it is the rebarbative rhetoric of May and the Tory Brexiteers that has provoked this response. Britain, for centuries a land identified with liberal internationalism, has turned into an international pariah.

There is understandable concern in European capitals at the way the UK Government is flirting with the divisive politics of of the European far right. Indeed, May's greatest admirer in European right now is the leader of the French National Front, Marine le Pen, who has congratulated Britain for taking a stand against the EU and immigration. Another fan is Geert Wilders, leader of the far-right Dutch Freedom Party, who is now the favourite to become Prime Minister of this (formerly) liberal country in March.

This is why continental leaders are becoming a kind of Europe United against the British Brexiteers. They realise, as Hollande put it last week, that this is not just “another crisis, it is the crisis” – an existential crisis for the European Union, and for liberal democratic politics in Europe. Viewed from Paris or Berlin, Britain is now a country led by delinquent racists who fight in Parliament and demonise foreign doctors and university students. The very idea of compiling lists of foreign workers in British factories evokes appalling images in countries that suffered Nazi rule within living memory.

Here in Scotland, this past week has been something of a turning point – a delayed reaction from the EU referendum result. When Scotland woke up on June 24 to discover that it was to be dragged unwillingly out of the European Union, there was a sense of unreality about it all. These things didn't happen, did they? Surely reason will prevail? It has taken this long to realise what the referendum meant: that the UK is now a very different country: one that has suffered something like a rightwing coup d'etat albeit without the bullets.

Of course there are those who claim that many Scots voters are themselves not particularly keen on the European Union or immigrants. This is probably true. But Scottish civil society, as it has been expressed in Scottish political parties, has always been united against the kind of attitudes that were on display at the Conservative conference last week. We need this unity now more than ever. The Scottish National Party, unlike many nationalist parties in Europe, has a very positive attitude to immigration and rejects all forms of racism and ethnic exceptionalism. But this is only a reflection of the prevailing attitudes in Scotland as a whole, which has undergone a huge transformation in its attitudes to outsiders since 1999.

But this is not simply a question of liberal sentiment and being welcoming to international students and EU doctors. There is also the the hard-headed question of Britain's and Scotland's economic wellbeing, which May has made very clear comes a poor second to controlling migration from Europe. “We are not leaving the European Union only to give up control of immigration again,” she told conference last week. “And we are not leaving only to return to the jurisdiction of the European Court of Justice.”

What that means is that Britain is going for the hardest Brexit on offer: a refusal to compromise on free movement in order to gain privileged access to the European single market – the destination of 50 per cent of British exports. Even the interests of the City of London, which needs “passporting” rights to operate in the eurozone, is being sidelined to the prejudices of little England. Brexiteers scoff that “Europe needs us more than we need them”. The Brexit Secretary, David Davis, insists that they'll have to open their borders to our goods or we won't take German cars.

He is partly right: tariff barriers on physical British goods are unlikely to be raised significantly, but that is not what the single market is really about. It is non-tariff barriers that are the real problem – especially for services. Britain's economy is now 80 per cent services and, unless there is regulatory harmony across the single market jurisdiction, we will be locked out of the main markets for the services of our architects, engineers, designers, management consultants, entertainment and creative industries as well as financial services. These are the things that post-industrial Britain does, which is why the single market is so important. Doubly so in Scotland where our dwindling, working-age population means we need the skills that immigrants bring.

Any country in the world can negotiate crude access to the single market on more or less favourable terms. Haiti has access, but pays stiff penalties. Canada has completed a deal on free trade with the EU, but which excludes services. Countries like Norway and Switzerland are members of the single market without being in the European Union, but they have to accept freedom of movement, the rule of the Court of Justice and pay a hefty fee for the privilege. May has drawn a very big red line under all that.

As this column has pointed out before, Theresa May has also drawn a big red line around Parliament. Westminster is to be sidelined, as Queen May uses the Royal Prerogative to initiate Article 50 ripping Britain out of Europe. The Great Repeal Act will be a fait accompli. Nor will the Scottish Parliament have any say on Brexit, even though the repeal of the 1972 European Communities Act will have a profound impact on the powers of the Scottish Parliament. Legislative consent will not be required, we are told, as protections on workers' rights, equality issues, environmental standards, agriculture, fisheries, energy – the whole compendium of EU laws which have hitherto applied in Scotland – are removed by executive fiat.

Brexit has been the greatest political upheaval in British politics in half a century, and it is also deepening the divide in the Union. Scottish voters may not relish the thought of another independence referendum, but there is no doubt that what has transpired in the past three months has fatally undermined support for the “caring sharing” UK that Gordon Brown and Better Together urged Scots to remain a part of two years ago. However, independence is for another day. Right now, Scotland needs to see her political parties set aside their differences and speak clearly with a united voice to the apostles of the Tory right: not in our name.