I'm sure you already have it marked in your diary: 22 May, the date of the next euro-elections.
If you haven't, you should have - because they'll be unusually important this year, both in the UK and in many others of the EU's 28 member states. (Yes, 28 - remember, Croatia joined last July.)
Why? Because, if current opinion polls are right, anti-EU parties will do exceptionally well in several countries, including here in Britain. Difficult though it may be to believe, Nigel Farage, the leader of UKIP, who revels in his beer-loving, ciggie-puffing, man-in-the-saloon-bar image, may soon be one of the most influential politicians in the country.
According to an analysis in last week's edition of The Economist, anti-EU parties could double the number of seats they hold in the 751-seat European parliament, up from 12% to as high as 25%. That would represent a fair-size political earthquake in Brussels, and could have a major knock-on effect on domestic politics as well.
There are, however, substantial differences between the various parties that can be grouped under the "anti-EU" banner. As The Economist points out, they range from the unashamed neo-Nazis of the Greek Golden Dawn party, to the ardently pro-Israel PVV party in the Netherlands. What they all have in common, in the words of The Economist, is that they are "populist and nationalist, that they have strong views on the EU, immigration and national sovereignty, and that as a result they are doing very well in the polls."
The Conservative MEP Daniel Hannan wrote in last week's Spectator: "The European Parliament has always had its fair share of extremists, eccentrics and outright, drooling loons ... But it's not just madmen on the rise. In country after country, genuine protest movements of left, right and centre are surging."
Some are out and out fascists. Others are rabidly anti-Islam. Or anti-foreigner. Or separatists. What they all represent, wherever they position themselves on the political spectrum, is a serious challenge to Brussels orthodoxy.
And even if you find much of what they say deeply distasteful, as I do, you may also think, as I do, that it's high time that someone delivered a powerful kick up the Brussels backside. For too long, the eurocrats have been both complacent and arrogant in their blind insistence that they, and only they, know the path to salvation and everlasting glory.
Just look at the results of a Gallup poll published on Wednesday. Asked "Do you approve or disapprove of the job performance of the leadership of the EU?", the message from voters was unmistakeable: the "approve" vote was down 32% in Spain, compared to 2008, before the euro crisis engulfed the EU; down 23% in Ireland; down 17 per cent in Sweden, and down 14% in Finland. Perhaps because we have largely stood aside from the euro currency crisis, the UK figure was down a mere 7%.
So here's the danger. A desire to frighten the Brussels establishment into recognising the crisis of credibility that they face could easily turn into support for some very nasty people. The challenge for Europe's mainstream politicians is to acknowledge the need for some fundamental rethinking, while drawing a clear line between rational scepticism and irrational bigotry.
Here in Britain, David Cameron will argue that this is precisely what he is doing, by demanding a renegotiation of parts of the UK's EU deal, and offering an in-out referendum once the haggling is over.
The truth, though, is that he and his party (after all, some things never change) are in a miserable mess over both the EU and immigration. On the one hand, Mr Cameron repeatedly stokes up fears of a wave of Romanian and Bulgarian migrants flooding across our borders (so far, there's been not so much as a trickle) - while on the other, his education minister Liz Truss happily admits that at least in some places, children from Poland are actually pushing up exam results in local schools.
The solution? Tell voters honestly what advantages being in the EU brings us, while acknowledging, equally honestly, that in return, we give up control of some domestic law-making. (Just as the people of Cornwall or Cumbria have to accept laws written in London...)
And stop pandering to prejudice over immigration: there's ample evidence that the overall impact is positive, and the answer in areas where there is added pressure on housing, schools, GPs, etc. is to invest in more services. Let us not forget that immigrants pay taxes too, and they are just as entitled as the rest of us to expect decent public services in return. (Declaration of interest: I am the son of immigrants.)
And one last plea: raise the minimum wage - and enforce it more effectively - so that there is less incentive for unscrupulous employers to hire illegal immigrants, and more incentive for British workers to take low-paid jobs. In the words of the conservative American businessman and commentator Ron Unz: "A much higher minimum wage would go a long way to reducing the ill effects of heavy immigration levels."
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