Enough! Let us put an end to this national humiliation. Around the world, Britain is increasingly viewed with pity or contempt. Brexit, were it to happen, would be the most consequential and gratuitous act of national self-harm in our recent history.

It is now crystal clear that there is no available deal with the rest of the European Union that can realise even a fraction of Brexit’s stated objectives. The only good way forward is for parliament to put the question back to the people, and for the people to decide that Britain should stay in the EU. To achieve that, everyone who possibly can needs to turn out in London tomorrow to march for a people’s vote.

Two years ago there was still a possibility that Theresa May might have built broad, across-the-aisle support around a soft Brexit, with Britain as a Greater Norway, staying in the single market and some version of a customs union. This would have been a poor second best, leaving the UK as a rule-taker rather than a rule-maker, but it might at that point have represented the least unhappiness of the greatest number.

I won’t be marching for a people’s vote. There has already been one | Suzanne Moore Read more

Whether a stronger prime minister could have pulled that off we shall never know. As soon as May decided to appease her hardline Tory Brexiteers, she put herself on the path to perdition. The ever more complicated, customised confusion in which she is now entangled, like a cat wrapping itself in a skein of wool, is a direct consequence of that decision to appease.

Ultimately I must be true to what we all know in our heads and feel in our hearts: the only good Brexit is no Brexit

I have worried in recent months about the apparent rigidity of Brussels’ negotiating stance, but the EU27 truly cannot be blamed for May going back on her own solemn commitment to have a backstop for Ireland unless and until other satisfactory arrangements are in place. Indeed, our European partners have now shown a willingness to go the extra kilometre, countenancing the whole of the UK staying in a backstop customs union and a longer transition period in which to negotiate the final deal.

Yet the only Brexit now available before the deadline of 29 March 2019 is a blindfold Brexit. The terms of the actual withdrawal would be agreed, but the entire future relationship would be sketched out only in the vaguest terms, in a so-called political declaration. As a former minister in the Department for Exiting the EU has observed, Britain would be walking off a gangplank into thin air.

Those who voted leave in 2016 are now all at sixes and sevens, but so are those who voted remain. Where there are two remainers you find three opinions. There are the “releavers” (now for leaving, in the name of respecting the referendum result), the experts struggling ingeniously to make the best of a bad job, and those still canvassing multiple variants of a softer Brexit. I have friends who take each of these positions, and I listen to them closely, but ultimately I must be true to what we all know in our heads and feel in our hearts: the only good Brexit is no Brexit.

Then comes a plethora of objections to a second referendum. It can’t be done. The EU27 won’t give us the extra time. It’s so complicated. What would be the question on the ballot paper? It would just prolong the agony. It would make a toxic atmosphere even more toxic. It wouldn’t solve anything.

Some of these objections are stronger than others. It will indeed be complicated to reach a simple choice. But far from prolonging the agony, this is the only way to shorten it. We have seen how difficult simply negotiating the withdrawal has been; it would take many more years to thrash out and implement a new trade agreement. This way, the nightmare could be over by next summer. We’re going to be a divided country for some time anyway, so let’s at least be a divided country in the right place. And if the majority of British voters decide we should stay in the EU, that will be a tremendous shot in the arm for the whole of Europe.

It is nonsense to say this would be undemocratic. Democracy does not mean “one people, one vote, once”. As the former Brexit minister David Davis memorably put it, a democracy is not a democracy if it can’t change its mind. Since we have had one popular vote, and have a representative democracy, the clearly legitimate path to a second referendum is through parliament.

Now a great parliamentary moment is approaching, one that will decide the future of this country for decades ahead. Most MPs are genuinely trying to work out what is the right thing to do – and then to calculate whether they can do the right thing and still get reselected and re-elected. Yet the finely balanced parliamentary arithmetic is such that it will only need a few brave spirits to ensure that whatever blindfold deal (or no-deal) May brings back from Brussels is defeated in the Commons’ “meaningful vote”. Then it will be for parliament to decide whether and how to put the question back to the people.

That’s why, after gathering at high noon in Park Lane, tomorrow’s march will end with speeches (from Sadiq Khan, Anna Soubry and Delia Smith, among others) in front of parliament. I participated in the first big people’s vote demonstration earlier this year, and while it was – with its pointed chants of “Where’s Jeremy Corbyn?” – substantial, colourful and jolly, the numbers were less than overwhelming. This time it needs to be much bigger.

Has the time come for remainers to compromise? | Martin Kettle Read more

So here’s the message:

If you agree with former prime minister John Major that the Brexit vote was “a colossal misjudgment that will diminish both the UK and the EU”, leaving Britain “weaker and poorer”, then march with us tomorrow. If you feel that the British have a historic and moral responsibility to help the island of Ireland move irrevocably beyond bloody sectarian conflict – march. If you want a liberal, progressive England, not the xenophobic, reactionary England of Tommy Robinson and the English Defence League – march. If you think the economic and cultural concerns of those who voted for Brexit must urgently be addressed, but that Brexit will do nothing to address them – march with us.

If you want your children and grandchildren not to have worse life chances than their parents – march. If you are under 30 and realise that it’s your future that is being sacrificed, as explained by the subversively named pro-referendum campaigns Our Future Our Choice (OFOC) and For Our Future’s Sake (FFS) – then, FFS, march. If you care about Europe as a whole, not just about Britain, and grasp what a serious threat Brexit is to the whole post-1945 project of building a better Europe – march. If you understand that this demonstration is just one small part of a much larger pushback against a worldwide anti-liberal counterrevolution – march. See you there.

• Timothy Garton Ash is a Guardian columnist