It seems almost impossible now to believe that Arsenal were top of the league on New Year’s Day. Now, instead of standing on the brink of their first championship since 2004, they are back where everyone expected them to be at the start of the season: clinging on desperately for a fourth-place finish. The sad reality for Arsenal is that a lightweight squad elevated by a star signing has reverted painfully to the mean. The same thing could yet happen to Ukip – and with disastrous consequences for Labour.

You might call it Labour’s 12 per cent strategy: the level at which Ukip does maximum harm to Tory prospects, and only minimal damage to Labour hopes. If Ukip can get to 12 per cent in 2015, then a government in even the palest shade of blue becomes an impossibility. And who could expect Ukip to fall below 12 per cent? Their party leader just took on the deputy prime minister in a scrap and won. People are still worried about immigration and worried about their bank balances, a far greater boon to UKIP than anything the European parliament does.

A new British Future report, published today, suggests that, for Ukip, a first-placed finish in the Euro elections will be as good as it gets. The European poll, far from being a bellwether, has now developed into an entirely different electoral ecosystem. Just as the Labour revival in Scotland in 2010 vanished into airy nothing before the SNP’s landslide in 2011, so too does the European election have an increasingly thin relation to the election that follows. The movement to proportional representation – and the fact that none of us really understand what the European parliament actually does – means that the whole thing is either an unnecessary chore or the opportunity to stick two fingers up at the establishment.

Since 1999 – the first European contest to be held under proportional representation – with one exception, the parties of Westminster have underperformed at Strasbourg. The exception came in 1999, when William Hague’s Conservatives ran on a platform that did well with the oddballs and rabid Europhobes who prefer European elections to World Cups – this is not colourful language, when British Future asked Ukip voters which they were looking forward to, they plumped overwhelmingly for the European poll, which either shows a desperate need to get out more or a brutal awareness of the many shortcomings of Roy Hodgson’s England – but did rather less well when put to the people who actually decide elections.

Time and time again, the European elections have proved the high watermark for anti-system parties. The BNP, the Greens, and even Ukip themselves have all ascended to new heights before crashing back into irrelevance in the contest to come. Even getting to eight per cent of the vote would be the Farage equivalent of 1997. Yes, Ukip have the advantage of a higher media profile than any of the anti-system parties of times past; but, given a megaphone, they show a surprising capacity to start calling people sluts, or expressing support for Vladimir Putin. A higher profile is a double-edged sword; and just as Cleggmania waned under the spotlight, so too will Faragism.

But what then would happen to Labour? After a torrid fortnight, the party has retained a narrow lead, with Ukip at around 15 per cent in the polls. Reduce their vote share even to eight per cent (assume for a moment that one percent of that ends up voting Labour, two per cent stays home and watches TV, and the remainder goes for David Cameron) and suddenly, Labour is behind. And that is before the Liberal Democrats try and take votes off Labour. That is before you factor out any voters who will either be drawn from Labour to Tory by Lynton Crosby; or simply put off voting entirely. Ukip’s voters are not going to stay the course; there is still time for that to benefit Ed Miliband, not David Cameron.