The Democratic People's Republic of Korea doesn't have many friends.

Mass starvation, hereditary dictatorships and a paranoid police state have a limited appeal if your name isn't Kim Jong-un. If you are a Western politician, though, "North Korea" is the synonym for all seasons.

It ought to be used with caution. Even by the grisly standards of totalitarianism, the top half of the Korean peninsula is a unique horror. Our politicians can't help themselves. Stuck for a way to describe the worst they can conjure, they reach for "the North Korea of ... [fill in blank]". Gordon Brown, who certainly knows better, has just joined the club.

Should the United Kingdom choose to leave the European Union, he declares, it would be selecting "the North Korea option, out in the cold with few friends, no influence, little new trade and even less new investment".

Reading this, a couple of thoughts spring to mind. One is, "Calm down, Gordon. Even if the rabid sceptics of Ukip and the Tory back-benches get their way, the UK won't dissolve into a famine-ridden Potemkin state with absolutely no sense of humour. Not overnight, at any rate."

Then the second thought intrudes. Mr Brown's melodrama aside, what would a so-called Brexit actually entail? Once the mists clear, the former Prime Minister's comments provide both a decent account of the likely economic costs, and what might be called the moral case for the UK remaining part of what Westminster politicians know as "Europe".

A lot of jobs and a lot of trade are at stake. A lot of potential influence is there to be won or lost. For Mr Brown, the prize is the advancement of "progressive British values". For him, the "culture war" at issue is no different from that fought - so he would have you believe - over Scottish independence. The fact that the Yes side in that argument was far more pro-European than the No fraternity does not detain him, but his broader point is fair enough. Euroscepticism is isolationism.

So why has this yet to feature to any degree in the election campaign? Even for Ukip, "Europe" has been reduced to little more than another excuse to prey on ignorance over immigration. Yet amid all the chatter - very revealing chatter - over the possibility of Labour being sustained in office by the Scottish National Party, an entirely plausible alternative is being overlooked.

The Conservatives could yet emerge as the largest of the Westminster parties in a hung parliament. Why not? If the polls are right, they remain contenders. If they come out ahead and manage to cobble together another coalition, we would be back on course for David Cameron's promised referendum in 2017. And voters will wonder why no one had much to say about the EU.

On the face of it, none of that seems likely. If Mr Cameron cannot win outright, who's he going to call? His LibDem friends are heading for a hiding, even if local loyalties prevail. Northern Ireland's Democratic Unionists - whose attitude towards Europe has softened somewhat of late, interestingly enough - cannot make up the shortfall. Ukip might attract the attention of London media, but no one thinks they will win more than, at most, five seats.

Things can change. In early April 2010 the Conservatives were regularly between six and 10 points ahead of Labour in the polls. Then came TV debates, "I agree with Nick", and a very rough patch for Mr Cameron in which the LibDems came close, for a week or so, to being the leading party. The Conservatives emerged in the end with a 7.2 per cent advantage over Labour, but a double-digit lead in January, and an overall majority, had been lost.

The obnoxious Labour-Unionist racket over the very thought that SNP MPs have the same rights as other parliamentarians overlooks what the Conservatives might still achieve. Scotland makes no difference to their chances, for one thing. For Mr Cameron's party the SNP only matters as a means to scare English voters away from Labour. If tabloids foaming with bloody froth are anything to go by, it might even work. If so, that EU referendum is once again on the cards.

Ironically enough, a YouGov poll last month found that British opinion has swung against withdrawal. Despite the travails of Greece and gleeful reports of eurozone woes, 45 per cent favoured remaining in the EU with 35 per cent against. Mr Brown might believe he and Labour are onto something.

Nevertheless, opinions on this matter tend to be "volatile": half a year ago, positions were reversed. What polls tend to show is that Scotland and London are more pro-European than other parts of the UK. Beyond that the front lines in any culture war are hard to discern. Even Mr Cameron's promise of improved membership terms from the EU is untested. Do voters know what that might (or might not) involve?

Meanwhile, the Prime Minister remains committed - he says - to a referendum, his sceptics remain obdurate, and Ukip does not waver. Who knows how the dominoes might fall? Let's say they fulfil Mr Brown's fears: another Tory coalition, a failed EU "renegotiation", a souring of public opinion, and a retreat to Brexitannia. Having made great play of the campaign to keep Scotland in one Union, Labour's former leader says nothing about the North British option (so to speak) if the rest of the UK decides to leave the EU.

A few gaps can be filled in. For one, a UK vote to quit would make an unholy mess of the devolution settlements for Scotland, Wales and Northern Ireland. EU law and the European human rights convention are incorporated in the statutes. These cannot be amended easily, if at all. The Good Friday Agreement meanwhile involves a treaty between the UK and the Republic of Ireland. There is far more to this than an "in-out" vote.

Last November, Nicola Sturgeon said that if a bill for a referendum came before the Commons the SNP would table an amendment requiring that the constituent nations of the UK should each have a vote. But if that amendment was defeated, what would follow? If the vote was allowed and the Scots chose to remain Europeans while others decided to quit the EU, what would remain besides the demand for another vote on independence?

Gordon Wilson, the former SNP leader, maintains that Ms Sturgeon would have a mandate for independence - fair warning having been given - if the UK majority chose EU withdrawal. In this UDI fantasy, another Scottish referendum is mentioned almost as an afterthought, but scant attention is paid to consent, or to the question of our continuing EU membership. To put it no higher, the notion doesn't count as useful.

Still, a pair of ex-leaders have between them performed one service by reminding us that the European issue has not disappeared just because the General Election has become a tight contest. Try all the permutations you like: one mark of the fissiparous state of the UK is in conflicting attitudes towards the EU. Those won't be resolved on May 7.