AS the Scottish opposition parties try to nail Alex Salmond over Scotland's membership of the EU after independence, they are failing dramatically to see the bigger picture.

There might not be an European Union for an independent Scotland to remain a part of if the eurozone debt crisis leads to a fracture between Germany and the rest. And even if the sovereign debt crisis is resolved, Britain's relationship to Europe after the next General Election could become so tenuous that Scotland would be more out than in the EU if it remains a part of the UK.

It is becoming increasingly clear that the UK Conservatives are, whatever David Cameron says, heading rapidly out of Europe. Last night's rebellion on the EU budget is only the latest manifestation of a deepening Euroscepticism among Tories at all levels. It's not just the Europhobic backbenchers who are growling and grumbling about the Brussels bureaucracy. The Foreign Secretary himself, William Hague, said recently: "If we cannot show that decision-making can flow back to national parliaments then the system will become democratically unsustainable". The UK Education Secretary, Michael Gove, says that if there were a referendum he would vote for leaving the EU altogether and claims half the Cabinet agree with him.

This marks a profound shift in British politics. The Tories have never been very keen on Europe – after all it's full of foreigners and dominated by the Germans. But Tory leaders including Margaret Thatcher have always accepted at least the economic case for remaining part of the European Union. Until now. As the eurozone plunges into ever-deeper crisis over the sovereign debt crisis the economic advantages seem less compelling. "Who wants to be part of a basket case?" ask senior Tory Eurosceptics, like David Davis and Liam Fox, who jointly launched the Fresh Start group last month.

Fresh Start believes that a chaotic disintegration of the eurozone, as the Mediterranean states rebel against German fiscal orthodoxy, will open the way for Britain to begin repatriating powers from Brussels, and turning Europe back into a free trade zone rather than a primordial United States of Europe. It is demanding, and will get, a referendum in the next Tory manifesto. David Cameron is doing his best to go with the flow, while not actually burning his Brussels boats. He has been arguing against any real-terms increase in the EU budget, but not an actual cut in Britain's contribution, which is what last night's Commons stushie was all about. The PM has also been trying to oppose Europe's plan for a financial transactions tax on the City to help pay for future EU bailouts. And of course he used his veto last December to block treaty changes. He says he wants to remain in Europe, but his body language says something different.

The Prime Minister is caught in a Euro pincer. On the one hand, his increasingly Eurosceptic party and Cabinet are looking for a break with Brussels. And on the other side, he faces increasingly unsympathetic EU leaders, like Francois Hollande and Angela Merkel, who are contemplating a break with Britain if we continue to oppose a banking union and other measures to centralise financial decision-making in Europe. That was the subtext of the remarks this week by the German finance Minister Wolfgang Schaeuble in Oxford when he urged Britain to get involved in the moves toward fiscal union. Some hope. The curmudgeon tendency is definitely in the ascendant in Westminster with even Labour calling for a reduction in the EU budget last night, and Ed Miliband openly flirting with Tory Eurosceptics. This can only end in tears.

So, Scotland's referendum on independence in Europe is likely to be followed by a UK referendum on independence from Europe. This is a fascinating twist to Scotland's constitutional story that no-one expected and leaves Scotland in an extremely odd place. It could be that remaining in the UK is the best way of leaving the EU, which would be welcomed in some quarters in Scotland, but not by many. Similarly, leaving the UK, on its present trajectory, might be the only sure way of remaining within the EU.

The Scottish opposition parties haven't quite grasped this yet, probably because most politicians in Scotland are instinctively pro-European and don't take the possibility of British withdrawal seriously. The Scottish voters too seem broadly content to be in Europe and don't show any signs of wanting to leave. ( Mind you no-one has asked them yet). But the visceral hostility that you find in sections of the UK press and politics, the "crimson tide" as Ed Miliband puts it, is almost completely absent in Scotland, and there seems little prospect of it emerging before any referendum on Europe. However, the two years running up to the Scottish independence referendum are likely to be marked by increasingly strident anti-European sentiments in Westminster.

The Edinburgh Agreement commits Scotland and England, under the Section 30 order, to work together "constructively" after the referendum whatever the outcome. The Scottish Government insists that this means both Scotland and the Rest of the UK have agreed to abide by existing treaty obligations, and that Scotland and England would both remain equally within the existing framework of EU law even after independence. However, this may be a presumption too far. No-one has asked what would happen if Britain votes, effectively, to leave the EU in say 2017, the likely date of any referendum on repatriation. Would an independent Scotland leave with the Rest of the UK, or would we remain as a separate state within the EU?

I don't have the answer to this, and I don't think anyone has. If I were one of the Government's legal officers I would be resisting requests to give any opinion on Scotland's place in Europe after independence on the grounds that it is increasingly difficult to predict what Britain's place will be in Europe. Certainly, Scotland cannot assume any longer that being part of the UK means being at the heart of Europe, or even in it. The debate on Europe is being turned upside down. Perhaps, the First Minister should be asking, not whether Scotland would remain in Europe, but how Scotland might get back into the European Union after Britain has effectively pulled out.