Twenty six years after he was caught by a hot mic denouncing the Eurosceptic “bastards” in his own cabinet, John Major has proved that he has not lost his knack for making news – and this time he very much knew the microphone was on.

The former Tory prime minister told the Today programme that any move to “prorogue”, or suspend, parliament in order to drive through a no-deal crash-out from the European Union – a move Boris Johnson has pointedly refused to rule out – would be “completely and utterly against parliamentary tradition”, adding that “I, for one, would be prepared to go and seek judicial review to prevent parliament being bypassed.” In other words, a former Tory PM just threatened to take the next Tory PM to court to stop a no-deal Brexit.

The legal scholars will debate the ins and outs of that idea, as they face the prospect that the judiciary will again be drawn into the Brexit quagmire sooner or later, but the immediate impact of this intervention will be political. Indeed, some moderate Tories might imagine this is the Exocet they’ve been waiting for, a threat of legal action by Major – together with his accusation that Johnson is putting party before country and his own career before both – at last putting a hole below the waterline of the Johnson campaign to become the next Conservative leader.

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That is a forlorn hope. Major’s move has almost certainly come too late, in that the selectorate in this contest, Tory party members, have received their ballot papers and many will already have cast their votes. But it’s too late in a deeper sense, in that the Conservatives stopped listening long ago to warnings like those their former leader issued this morning.

Indeed, Major’s move will doubtless galvanise the Brexit ultras who dominate today’s Tory party. They will simply add him to the long list of “enemies of the people” who stand in the way of their Brexit dream, along with the judges, the BBC, the CBI, the TUC, the experts, business and those Tory cabinet ministers – including, say, Michael Gove, who with Boris Johnson led the leave campaign in 2016 – who are now deemed to lack sufficient faith.

For this is the new Brexit dividing line. Back in Major’s day, Tories were split between those who wanted to rule out Britain joining the euro forever, and those who only wanted to rule it out for the lifetime of a single parliament. Now merely leaving the European Union itself is not enough; nor even is leaving the EU without a deal, a no-deal Brexit, enough. No, to be a true Brexiteer today, you must be ready to leave the EU without a deal even if that means denying MPs a say. In the macho politics of Brexit, a willingness to blow up centuries of parliamentary democracy is the latest virility test.

In this climate, it actually helps Johnson to be pitted against a man whom hardcore Brexiters see as a Brussels-loving, remainer weakling. Major’s calm reasoning will be dismissed as mere defeatism by a Tory tribe that wants to hear fantasies, such as the latest one served up by Johnson during last night’s TV debate against Jeremy Hunt, when, in defiance of all the evidence, he promised that, with the right preparations, a no-deal exit from the EU would be “vanishingly inexpensive”.

So Major’s legal threat will not change the direction of a contest apparently destined to put Johnson in Downing Street, even if it does see an escalation of blue-on-blue hostilities – and note the Johnson camp’s declaration that Major “has gone completely bonkers” – already intensified by Hunt’s combative performance last night. But it has value, nonetheless.

First, it might help prevent a no-deal crash-out, by forcing the next PM to realise that obstacles stand in the way of every version of that scenario – whether it’s a no-confidence vote in the Commons or a verdict in the high court. And, second, it highlights the glaring hypocrisy of the Brexiter case.

Recall that in the spring of 2016, the leavers said we had to exit the EU for the sake of parliamentary sovereignty, to restore once more the right of MPs to have the final say on how Britain is governed. And yet here we are, three years later, with those same leavers insisting on the right to cut MPs out of this decision altogether. Nothing better confirms that Brexit has become a fetish, one to which every other principle has been subordinated – including the conservative principle of preserving a constitution that has endured for more than three centuries.

It is bleakly appropriate that a former Conservative leader and prime minister has reminded us of that fact. Not for the first time, John Major has done his country a public service.

• Jonathan Freedland is a Guardian columnist