Slowly but surely, what was unthinkable is becoming normalised. The last few days have seen a concerted attempt to repackage a no-deal outcome from Brexit talks as being somehow tolerable.

In a way, this makes for a welcome change. In March, Brexit secretary David Davis told a Commons select committee there had been no preparation at all for a no-deal outcome. "We could not quantify the outcome," he said, in a classic example of clever people using complicated words to mask the fact that what they are saying is outrageously stupid.

This was remarkable. No-deal is the default outcome. This is partly what makes Article 50 so dangerous. It demands that a huge political and economic negotiation is undertaken to an impossible timetable, with failure weighing disproportionately on the smaller partner. Former civil servants were aghast at the idea that no preparation had been done for the default outcome. That, after all, is how the majority of political planning operates: it works out from the default to start mapping out the effect of actions to change it.

Now things have changed. This week, no-deal has come into its own. The government rushed out white papers on trade and customs in which it outlines what the preparations would look like. Theresa May made clear it was one of the options Britain could take, saying "it is also our responsibility as a government to prepare for every eventuality". A large minority of Tory MPs seem to be struggling to mask their enthusiasm about it. On radio, the one or two business leaders who could countenance it are wheeled out to say it'll be fine, in exactly the same manner as they assured us last year we'd definitely get a deal with the EU. There is an appearance of 'balance', of roughly equal validity to both sides of the debate. Online, seemingly sensible Conservative commentators say May's approach to no-deal prep is "wise", whereas allowing temporary ECJ jurisdiction during transition is "dangerous".

If only they really were evaluating no-deal. But dig past the chatter and look at the work and you'll find nothing there.

10 Here's the hardcore "no deal" porn for Brexit extremists - in a brown paper envelope marked "contingency scenario" to get past censors. pic.twitter.com/tE0NmOohjo — Steve Peers (@StevePeers) October 9, 2017

12 The government can't explicitly admit that "no deal" necessarily means a hard border re Northern Ireland/Ireland. But 5.45 comes close. pic.twitter.com/H87H7gsVs3 — Steve Peers (@StevePeers) October 9, 2017

This is not preparation, or even a contingency plan. It is a mild and very short overview of areas of concern. The language is soothing. We'd just have to fill out a few more forms. And the border in Ireland will be fine, because everyone wants it to be.

This is a PR exercise. It's not even really being undertaken to convince the Europeans we'd do it. They know we wouldn't - and if we would, we'd be the victims. This is to satisfy the crazed emotional urges of backbench Tory MPs who have wilfully failed to understand the consequences of the political demands they are making. It's disaster porn for nationalist maniacs.

The reality of no-deal is worse than most members of the public could ever imagine. For most people, no-deal sounds like the status quo, just with no special benefits. That's why the phrase 'no deal is better than a bad deal' was so seductive. But in truth, no-deal is much, much worse than the status quo.

This is Brian Strutton, general secretary of the British Airline Pilots Association (Balpa) on no-deal. You'll note he is less sanguine about it than Tory MPs or right-wing bloggers.

"The entire UK aviation sector which employs nearly a million people and carries more than 250 million passengers per annum would be devastated by a Brexit 'no deal'. UK airlines could find they have to stop flying – it's that serious. It is utter madness for anyone to think that a Brexit 'no deal' would be anything but a total disaster for our world leading UK aviation sector and beyond. After all, without air cargo we will not be able to export or import freely."

Pulling out of the EU aviation system without a stop-gap arrangement would mean air carriers can only fly between the UK and their country of origin. UK airlines would lose their ability to fly between other EU member states. And that's not even to mention the legal requirements by third parties, like the US demand for passenger data ahead of flights, which is currently under an EU umbrella. Unless there is a deal on that, there will be no flights from the UK to the US either.

A no-deal outcome means a border in Ireland. The British can claim they would not set one up - and they can mean it - but someone is going to take the Republic of Ireland to the ECJ because it is allowing a massive open channel into the single market by a third party state, and they are going to win that case. Then, as point of law, a border will have to be built. This is the reality.

No-deal means that punishing tariffs will be imposed on agricultural goods. British food producers will lose competitive access to their largest export market, so they will try to raise their domestic prices to make up for it. Most will go out of business. In manufacturing, products will soar in price. It's not just the ten per cent tariff on the finished car, but the tariffs on the component parts too. In addition, there are heavy bureaucratic costs to the country-of-origin checks manufacturers will have to undertake. The cost of the product will rise steeply. Fewer will be sold. Businesses will go bust. As Brexiter Peter North wrote yesterday:

"In the first year or so we are going to lose a lot of manufacturing. Virtually all JIT export manufacturing will fold inside a year."

According to the World Bank, no-deal would see a 50% reduction in Britain's trade with goods with the EU and a 62% reduction in its trade in services.

This is the reality.

It's why the government is desperately trying to keep secret the 50 sectoral impact assessments it conducted. They have refused to answer questions in the Commons about them. They have refused to respond to freedom of Information requests about them. Last night, 120 MPs wrote demanding they publish then. We are unlikely to see any change in the response.

They cannot publish them because to do so conceded that they are pursuing an insane strategy in which the default outcome is catastrophic. It is far more extreme than anything proposed by Jeremy Corbyn's supposedly Trotskyist political initiative. It would cost hundreds of thousands of predominantly working and lower-middle class jobs, it would devastate investment, it would sabotage British public finances, and trigger a prolonged period of crushing austerity. There is no mandate for it and there is no argument for it: it is intolerable. The fact it is mentioned now as a possible outcome is evidence that the British political class has gone completely insane.

Ian Dunt is the editor of Politics.co.uk. His book - Brexit: What The Hell Happens Now? - is available now.

The opinions in politics.co.uk's Comment and Analysis section are those of the author and are no reflection of the views of the website or its owners