Hans Christian Andersen did not write a sequel to the Emperor’s New Clothes, depicting the aftermath of the potentate’s humiliating naked parade through town. There is no record of the failed parliamentary votes to validate imaginary robes, nor of the talks on patterns and texture with the leader of the opposition. We can only imagine how the swindling tailors carried on peddling their wares, capturing a growing share of the clothing trade with their nonexistent fabric.

And so Nigel Farage’s magical glad-rags roadshow is forecast to outperform all other parties in this week’s European elections. His product is a silky Brexit that moulds itself to the contours of any Eurosceptic preference, delivered by pure will, costing nothing. This is not an original pitch. Ukip topped the last MEP ballot in 2014 with 27% of the vote. In 2016, the official leave campaign’s package of glossy fictions won a national majority.

It isn’t news that many British voters want out of Europe and don’t really care how it is done. Nor is it surprising that people are angry that it is taking much longer than promised. But it is remarkable that the whole period of government visibly striving to extricate the UK safely from the EU has left so little imprint on public debate about what Brexit involves. The Westminster lexicon got bloated on junk terms – “max-fac”, “Chequers plan”, “Brady amendment”, “Malthouse compromise” – none of which nourished any understanding of what happens when a member state cancels its treaty obligations.

British politics collided with reality and bounced off. Now it is boinging around roughly where it was in 2016: Tory Eurosceptics and Faragists still talk about leaving in glib, simplistic terms and face no sustained challenge. They cast Brexit as a one-off event and a settled destination, a single bound into a promised land, when it has proved already to be an arduous, open-ended process. The referendum result posed more questions than it answered and, three years later – long enough for an undergraduate degree – the leaver class of 2019 hasn’t graduated beyond “Brexit means Brexit”.

It can be instructive, ahead of Thursday’s vote, to remove the “B” word altogether when considering what the various sides are offering. Labour seeks a customs union with the EU, unilateral submission to single market rules (without meaningful say in how they are set) and an end to free movement. Theresa May’s deal delivers Labour’s preferences, but relies on the convoluted mechanism of the backstop to get into a customs union, while pretending that may never happen. The Liberal Democrats, Greens, Change UK, Scottish and Welsh nationalists support staying in the EU. This premium package, featuring bespoke opt-outs and a budget rebate, is arguably better even than the standard membership terms enjoyed by 27 other European states.

Brexit party leader Nigel Farage. Photograph: Scott Heppell/Reuters

Farage advocates trading on World Trade Organization terms – an apparatus no country in the world considers to be sufficient basis for modern commerce. The plan is to then sign new free-trade deals, which in reality would require immediate and urgent negotiations with Brussels. The no-deal method incinerates a highly developed platform for borderless European transactions in order to build a flimsier one from scratch and from a weaker position. It imperils swathes of British industry and projects a global image of roguish disregard for international agreement. It will not get easier to complete future deals as a country that has trumpeted contempt for deals that have already been negotiated.

In short, England’s main opposition party refuses to argue for the best item on the menu, and the governing party is just a few leadership hustings short of embracing the worst.

Lots of bad ideas become popular, but the failure of mainstream politicians to demolish a truly appalling Brexit prospectus reflects intellectual debilitation and cowardice on an epic scale. There is plenty of blame to go around but the biggest portion belongs to the prime minister. It is May who said over and over again that “no deal is better than a bad deal”, lending the authority of her office to a lie. It began as a bluff, based on a mistaken calculation that Brussels negotiators would be intimidated by Britain asserting willingness to inflict harm on itself.

Towards the end of the original article 50 negotiating period it was no longer clear that May was bluffing. In the run-up to the March deadline, I asked cabinet ministers if they thought the prime minister was capable of taking the country over the cliff edge. None had a confident answer.

The most plausible account was of a leader torn between rival conceptions of her duty: she felt compelled to satisfy the referendum result at any cost, but compelled also not to break the country. She was persuaded in the end that a chaotic Brexit could trigger a cascade of events leading to a united Ireland and an independent Scotland.

But when parliament demanded an article 50 extension, May acquiesced with graceless resentment. She hid her own judgment. She used MPs who refused to indulge insanity as human shields to deflect public frustration away from herself. She insinuates that Europhile saboteurs blocked the path to no deal, lacking the courage to say that path should never be taken.

Now, as power drains away, she plans to parade the familiar, tattered Brexit through parliament one last time, but dressed as a “new offer”, adorned with legislative trinkets to draw eyes away from the old offer underneath. She even promises a glimpse of a path to another referendum, on the condition that MPs agree first to endorse the thing they have rejected three times already. It could be her last act in Downing Street: frantically writing policy cheques that would be torn up by a successor or bounce at a Brussels negotiating table.

The embers of May’s reputation are all but ash, and still she cannot bring herself to breathe a valedictory glow of honesty into them. Her personal authority might be spent, but there is a vestige of power in the Downing Street pulpit she clings to. Yet still she will not use it to tell the truth. Then her cracked, hollow voice will be drowned in the pompous roar of pretenders to the throne, each boasting that theirs are the brightest, most luxurious items from the fabled store where bogus Brexit yarns are spun.

• Rafael Behr is a Guardian columnist