The calendar is clear enough.

On May 22, European Parliament elections; on September 18, the independence referendum; on May 7, 2015, a United Kingdom General Election. When the dust from that lot settles, if it settles, Scotland will go back to the polls on May 5, 2016. It should be enough to be going on with.

A large, vocal and relentless group of Tory MPs and peers does not agree. As though setting up the last in a line of political dominoes, they are determined to put their distaste for the European Union to the referendum test in 2017. What's more, they insist on a straight choice: in or out, once and for all. Most of them believe that, in the event of a plebiscite, a British withdrawal is a certainty.

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David Cameron has promised this wing of his party their heart's desire on this, but they do not, let's be blunt, trust him much. So James Wharton, MP for Stockton South, has put a bill through parliament to tie his Prime Minister's hands by giving a legal standing to a Downing Street pledge. Yesterday, the European Union (Referendum) Bill reached the Lords.

You could call this a little presumptuous; you could call it fantasy politics. The political game of "if A then B then C" has never been quite so complex. The possibilities, if not exactly endless, are so numerous they could make a voter's head swim. Whether Tory Eurosceptics have even bothered to attempt to think through the variables is a moot point. But in several plausible scenarios the next three years could see these islands changed utterly.

Start at the beginning. Ukip has not a single MP to its name but you could be forgiven for thinking otherwise, judging by the party's ubiquity in broadcast studios and the print media. There are simple enough reasons for that. In England, anti-European and anti-immigrant sentiment has found its blustering voice. Each of the main Westminster parties is losing support to Nigel Farage and his ragtag army but the Tories are hurting badly. The Euro-elections are expected to be a Ukip triumph.

What flows from that? Nothing very pleasant. Mr Farage no longer pretends to care about the demonstrable economic contributions made by immigrants. For him - the language is scarcely coded - the issue is now "cultural". In response, Labour has already begun to mutter about "restricting" arrivals even from the EU, but the Tory reaction to Ukip advances in May scarcely needs to be predicted. In military terms, it will amount to a flanking manoeuvre.

That's democracy, you might say. If such is the popular will, so be it. But Mr Farage and his friends are not exactly esteemed in Scotland. Election results and opinion polls say, in fact, that they are held in near-contempt. Yet this resentful, ramshackle, xenophobic movement could soon be driving the policies of a party of government, whatever Scots might think.

Which brings us to the second domino. Will voters here be troubled by the rise of Ukip in the south? They ought to be, but apathy towards European Parliament elections is a well-established phenomenon.

Could the spectacle of Mr Farage calling the shots at Westminster influence Scotland's subsequent referendum campaign? Those working for Yes might like to believe it, but the simple truth is that we don't know. It counts as still another possibility.

Then, regardless, comes the referendum itself. The opinion polls are readily available but I stick to the belief that things won't begin to become clear until the spring. What can be noted are the continued assertions from Better Together (for whatever motive) that the result will be closer than polls suggest. Influenced by Ukip? Influenced by the certainty that a large body of Tory MPs will take Scotland out of the EU if we vote No? It will surely be a surprise if such factors have no effect.

One consequences of a Yes vote, nevertheless, is that it would leave Scotland's MPs in the most peculiar position imaginable. The Labour regiment would be working to put Ed Miliband into Downing Street knowing that his majority could be cut by 41 within 18 months of a Yes vote. Current calculations - calculations I do not trust in the slightest - say Labour will be ahead by 80-odd seats after the 2015 Westminster elections. But no-one is sure what happens if Scots vote Yes and Mr Miliband manages only a 30-odd seat majority.

A year later, Scotland will pass judgment on the winners and losers in the independence referendum when we go back to the polls to choose MSPs. One domino will fall upon another. All the while - and this you can guarantee - Tory backbench frenzy over "Europe" will continue unabated. Labour's response to that is these days another imponderable. The signs are that, as usual, the party will bend with the prevailing wind in some manner. It, too, has its divisions over the EU.

If we have voted Yes, our problems in that regard will be solved. The scaremongering over European membership will be seen for the campaign prattle it is. But if we have voted No, another democratic "peculiarity" awaits. Scotland's place in Europe will depend on Mr Miliband and his resolve, or on Ukip and the sceptics. Scots seem to be inclined to remain within the EU, according to some scarce polling, but they risk having no real say in the matter if they stick with the UK's economic and political union.

At every turn there is the chance of an unholy mess for everyone in these islands. Nevertheless, the uncertainty so often decried by Better Together has far less to do with the campaign for independence than with the machinations of Tory back-benchers and Ukip. Unionists who tout "the best of both worlds" are hard put to say how that world might look come 2017. The real gamble is to hope that Mr Miliband's Labour will provide a refuge from the hysteria over Europe and assorted foreigners.

As 75 peers queued yesterday to give their opinions on Mr Wharton's bill it was clear, not for the first time, that swathes of the Tory Party are perfectly in step with UKIP. The economic arguments over Europe and its importance to UK and Scottish trade cut no ice with these people.

They prefer to talk instead of "liberty from Brussels" and the repatriation of powers, as often as not forgetting that those powers were ceded by Tory governments. Some of these same politicians would be perfectly content to see Scotland vote Yes if it secured their shrunken world.

Mr Cameron hopes to placate them before 2017 with his own demands for EU concessions. Most of these, as Scots would do well to remember, involve the rights of workers. These will not be improved if the Prime Minister has his way. Nor - and you can count on it - will the sceptics be satisfied.

They aim to take England out of Europe no matter what. If Scots vote No to independence and choose to tag along, they will be signing up for the most uncertain future imaginable. With Ukip crowing at every turn.