Many Brexiteers call it Project Fear goal Greg Clark says it's just the reality of his conversations with businesses and the world will be lost if the next prime minister presses with a no-deal Brexit.

In his opinion, Mr. Clark did not pull out his punches about the damage of a business deal. last three years is not "somehow forgotten" in the rush to get Brexit across the line.

His Brexiteer opponents believe that he – together with Philip Hammond Chancellor – have dragged their heels over no-deal planning and sought after to the UK's departure from the EU.

Mr Clark says he has not, pointing out he voted for Theresa May's deal three times.

Boris Johnson
Boris Johnson says Brexit must happen before the end of October

But it's clear that it's not going to hit the road. Brexit is not just foolish but deeply dangerous. He argues the government can not just mitigate the risk of a no-deal and argues Boris Johnson's view that a no-deal becomes "vanishingly inexpensive if we prepare".

He points out that while he can help businesses get their paperwork in order to be able to buy goods, they are things "you just can not prepare for" and gives the example of just-in-time because production in which parts arrive factories sometimes with just four hours' notice. Car makers do not have warehouses to stockpile these shares so disruption to the flow of goods to the world: "To leave abruptly without a deal would be very disruptive in ways that you can not guide against."

But for Brexiteer colleagues, Mr Clark's warnings are a little more than a re-run of 2016 when George Osborne's Treasury warned of Brexit Armageddon if the UK voted to leave the EU. There was a budget for a £ 30bn black hole in the public finances caused by a plunging economy. It never happened, so you can understand the economic warnings of a no-deal now fall on deaf ears.

This is ideological warfare in which those who are backing away are those who want to remain in being overly pessimistic. Those who are concerned about the fall-out of no-deal, believe their opponents are swapping facts for beliefs.

As Brexit supporter and Conservative MP Mark Francois told me, he believes the economic risk has been exaggerated and Mr Clark's job loss warnings overdone. "He's an arch Remainer." "He's still going to change his mind." Once we've left, I'm going to believe he'll be right and he'll be wrong. "

What can all politicians at least agree on is the result of the referendum pointed to a breach of the EU, but it is also important that the EU should stay in the EU. It has not worked out like this. Parliament has polarized and views have hardened. Something that was once unthinkable – a no-deal Brexit – has become a very real outcome.

And the two sides argue about no-deal risk, in reality the vast majority of Tory MPs hope it will not be possible to test them and their next prime minster can find a way to get a deal across the line. Because if no-deal ends up the only way to avoid further Brexit delay, there will be a cost. And the Conservatives might find that the price they pay is electoral oblivion if Mr Clark's warnings come true.