22/02/2016 07:28 GMT | Updated 22/02/2017 05:12 GMT

Boris and the EU Referendum - How and Why Remain Campaigners Can Have The Last Laugh.

David Cameron's sales pitch for a Remain vote in the EU referendum, saw him repeatedly using the phrase he "didn't love Europe."

Now hypocritical Boris Johnson says he "does love Brussels," along with the fine wines and expensive holidays, but has announced he will campaign for Britain to leave the EU.

The first reaction is that this is simply final confirmation that there is no love lost between the Tory leader and the man who would replace him.

Yesterday's declaration should actually be understood as Boris Johnson's formal announcement of his campaign to lead the Conservative Party.

It has little or nothing to do with Europe.

And it is sad that it risks obscuring the strong case for Britain to remain in the European Union, by turning at least part of the campaign in to a proxy war between Johnson and George Osborne, for which of the two is best placed to succeed Cameron.

For Labour too, the stakes just got higher.

Ed Miliband had already done private work on the case against Boris, in case there had been a snap change in the Tory leadership, prior to the last General Election.

Now Labour must defeat the 'leave' argument, not simply in the British national interest, but also because my party won't want a likely principal opponent for the next General Election to be emboldened by an early victory.

But it is hypocrisy which can be our early weapon to defeat Johnson and his argument.

The Brussels correspondent of the Daily Telegraph when I was first elected as Euro MP, I have many times heard and read Johnson describing himself as "pro-European."

Famously, he once said this to a national newspaper, adding that he was in favour of a European Community which allowed him to "generally make love to foreign women."

But if Johnson wins the EU argument now, it will be Britain which will be screwed.

His full name is Alexander Boris de Pfeffel Johnson, reflecting his German ancestry. A television programme about his family history, revealed that Johnson was descended from a string of counts and countesses, barons and baronesses, from all over Europe.

Describing himself as a "Euro toff", perhaps Johnson's biggest objection to the European Union is that he and his class don't run everything on the continent any longer?

Johnson's cynicism is further magnified, when those of us who are from outside London, should be reminded that he is still Mayor of our nation's capital city.

London is perhaps that part of our country which most benefits from the European Union. Johnson's own adviser Gerard Lyons, said again last week how much the City itself is "pro-EU". The economic study which Johnson commissioned himself - the Lyons Report - showed how London would lose £26 billion in less than twenty years, if British membership of the European Union were to end.

There is no clearer evidence that Johnson is putting his personal ambition before the interests of the people we are all supposed to represent.

Meanwhile when Johnson launched his own proposals for reforms to the European Union, many of them - including opting-out from the provision for ever closer union, a card system for national parliaments and completion of the single market in services - are proposals precisely included in the package agreed by EU leaders last week.

Of course, Johnson wanted to go further in some areas, but "scrapping social and environmental legislation" will never be acceptable to Labour ears, and come as no surprise from the same source who unsuccessfully led opposition to the EU 'cap' on bankers' bonuses.

The Tory Right and UKIP share a hatred for European regulation, irrespective of its merits.

Boris Johnson and Nigel Farage also have one other thing in common - as the media darlings of television producers. Because of this, both men too often escape serious scrutiny of their political argument.

So that is now the challenge for the 'remain' side in the EU referendum campaign.

The outcome is too important to be played for laughs.

So let us challenge the Boris Johnson who once described the European Union as a "prototype to Hitler's wartime Reich." The European Union has entrenched peace and democracy in Europe, and is the most important bulwark against backsliding in Europe's troubled history - which the biographer of Winston Churchill should not be allowed to ignore.

And let us challenge the Boris Johnson who said one thing to journalists for his own political ends yesterday, but in an effort to sell that very same book in Germany last year, told the 'Der Spiegel' newspaper: "Look, we can't leave Europe. We're part of the European Continent. We're always going to be a part of Europe psychologically."

He was right then, he is wrong now.

I think we can all understand the psychology of Mr Johnson.

But it is a referendum victory for Britain to remain in the European Union, which can provide us with the last laugh.

Richard Howitt MEP is Labour Member of the European Parliament for the East of England and Chair of the European Parliamentary Labour Party.