The week the claws finally came out for Boris Johnson

The claws have finally come out for Boris Johnson. After eight years in which he has been treated as little more than a comic figure to be occasionally gently prodded, Boris is finally feeling the sharp end of the stick.

The turning point came at the end of last month when he decided to back the campaign to leave Europe. From the second he made his announcement, the coverage of the London mayor immediately changed.

His press conference announcing his decision was widely savaged for being "shambolic", while his column backing Brexit was ridiculed for errors and "incoherence". Meanwhile the prime minister publicly accused him of pursuing selfish ambition in the House of Commons, while other Conservative figures lined up to heap abuse and derision on him. One of the most outspoken was former Conservative MP Jerry Hayes, who described Johnson as a "Copper-bottomed, double-dealing hypocritical little shit," adding that "The press will destroy him."

Sure enough the British press, which for years had taken little notice of him apart from the occasional photo of him on a zipwire and the occasional piece referring to his prime ministerial ambitions, suddenly started holding him up to scrutiny. Andrew Marr, who has long been Johnson's interviewer of choice, was notably far more aggressive with him on Sunday's show than usual. More importantly, the press reaction was overwhelmingly negative. Westminster commentators were almost unanimous in rating his performance poorly. Even The Sun, which has been more supportive of the London mayor than any other national newspaper, said he was "lost in a cloud of Brexit waffle". Meanwhile, the Conservative's Scottish leader, Ruth Davidson, said the mayor had "flounder[ed]" on air, adding "Not sure the bumble-bluster, kitten smirk, tangent-bombast routine is cutting through."

Even Boris's record as mayor, which has received less scrutiny from the British press than most obscure third world dictatorships, is now finally starting to draw attention, with his questionable role in authorising and funding the construction of the Garden Bridge developing into a real scandal.

And today the BBC uncovered an email from Boris's chief of staff, telling senior aides not to contradict Johnson on the subject of the EU. The message, emerging within days of Boris attacking the Remain campaign for trying to "quash dissent" could not have come at a worse time for him. The image of Boris as a flip-flopping politician who backed Brexit purely out of self-interest, had already widely taken hold in the public mind. Now the image of him as a hypocrite risks taking hold as well.

For years now, Boris has been rated as the most popular politician in the country. His Conservative rivals have long grumbled that this is due to his largely ceremonial position as London mayor. As he is about to leave City Hall and enter national politics, the long-awaited scrutiny will inevitably fall heavier on him.

But the wave of attacks crashing over him right now are not just being orchestrated by those who see him as a potential rival. By backing Brexit, Boris made himself an enemy, not just of the prime minister and chancellor, but of the vast majority of the British establishment. For the past eight years Boris has been a tame champion of that establishment, stepping forward to defend the financial industry, the super-wealthy and the worst elements of Fleet Street. With his 'plain-speaking' reputation, he may have sounded unlike any other mainstream politician but, when it came to the issues, he was as bog-standard as it was possible to be.

His support for Brexit has changed all that. Not only is he fair game for attacks from internal rivals and the bulk of the wider establishment, he is now their primary target. How he reacts to those attacks will decide his future. If he responds well then he has an excellent chance of fulfilling his life-long ambitions. If he continues to respond poorly then he will go down in history as the latest in a very long line of potential prime ministers who never quite made the grade.