On Tuesday, Boris Johnson made his latest thinly veiled bid for the Tory leadership, outlining his own distinctive vision of Britain's relationship with the EU ahead of David Cameron's crucial, defining speech on Europe later this month. He called for Britain's EU membership to be "boiled down to the single market", scrapping the social chapter and other pesky regulations from Brussels. He then went on to suggest that Britain should join the "outer tier" of Europe along with Switzerland and Norway, while maintaining an active role in shaping single market legislation.

Never mind that neither Norway nor Switzerland's relationship with the EU is purely based on free trade, never mind that minimum social and employment standards are an inextricable part of the single market: Johnson knows how to play the keys of Eurosceptic press like a concert pianist. This may just be because when it comes to British Euroscepticism, Boris Johnson invented the Steinway. As Sonia Purnell points out in her biography, during his stint as the Telegraph's Brussels correspondent from 1989 to 1995, Johnson pioneered the kind of acerbic anti-European polemicism that dominates much of the press today. One of his articles referred to the "noxious aromas emanating from Holland", a reference to the fumes of Dutch pig manure reportedly being detected in Essex. Another accused a French minister of trying to ban the use of certain English words.

The Murdoch newspapers in particular followed Johnson's lead. In a BBC poll on the most memorable front page of the century, Johnson paid tribute to this by nominating an edition of the Sun from 1990 which called on readers to "tell the filthy French to frog off". The article went on to say that "they insult us, burn our lambs, flood our country with dodgy food and plot to abolish the dear old pound".

Johnson last night described David Cameron's stance on eurozone integration as "intellectualy and morally wrong," calling for a policy rooted solely in Britain's long-term interests. Yet when it come to Euroscepticism in the press, vested interests are likely to play a much stronger role. Rupert Murdoch has a deep commercial and ideological aversion to the EU, viewing its anti-monopoly laws as a threat to the expansion of his media empire and its social policies as antithetical to his economically neoliberal worldview. Other newspaper proprietors, the Barclay brothers of the Daily Telegraph, Richard Desmond of the Daily Express, and Lord Rothermere of the Daily Mail, have similar political and business interests in advocating British withdrawal from the EU.

Undoubtedly, the economic pressures facing newspapers have also played a part. Not one of the rightwing tabloids currently has a full-time correspondent in Brussels, leading to a reliance on freelance reporters who are in constant competition to come up with the most ludicrous story about the EU. Having helped foster deeply Eurosceptic attitudes, the rightwing press must now compete to pander to them.

As a consequence, over the past two decades the EU has been subjected to a daily barrage of attacks, ranging from gross exaggeration to outright fabrication. Screaming headlines denounce the latest sinister plot from Brussels, whether it is banning selling eggs by the dozen, stopping children from blowing up balloons, or even plotting to liquify corpses and pour them down the drain. Many of these "Euro myths" have now become deeply embedded in the popular imagination. It is perhaps no coincidence that 18- to 24-year-olds, who are more likely to get their news online than from traditional print media, are the only UK age group in which a majority would vote to stay in the EU.

Johnson now finds himself wrestling with the Eurosceptic monster he has helped to create. The mayor of London is torn between the broadly pro-European voices of the City of London and business leaders, who want to see their interests protected through constructive engagement with the EU, and the Tory grassroots, who are baying for the blood of Brussels bureaucrats. Already, he has faced criticism from those in the party who see his latest speech as a betrayal of his previous support for a straight in-out referendum.

Nevertheless, as a seasoned Eurosceptic journalist himself, Johnson knows all too well how to play the rightwing press, which has come out in force to support his call for partial disengagement. His description of the euro as a "calamitous project" could have come straight from a Daily Mail editorial. Crucially, by giving the tabloids just enough red meat, he has been able to speak out against a British exit without coming under fire.

The recent conclusions of the Leveson inquiry have shown how Murdoch and other media moguls have been able to significantly influence Britain's policy on the EU, pressuring successive governments to adopt a particular line. In Boris Johnson, however, they may have just met their match.