Jo Johnson's warnings on Brexit are serious this time – and so are his brother's

This could be the decisive week for Brexit: MPs need to understand that the range of options may be wider than those presented by the prime minister

Even if you have heard it all before and do not want to read another word about backstops, Mr Johnson is not sounding a false alarm (PA)

Wolf! Wolf! cried the boyish Jo Johnson. But the villagers had heard it all before, so they paid no more than polite attention. They had been told so many times before that the moment of decision was upon them, and that the catastrophe was about to break around them.

But now we really are facing a moment of crisis. Theresa May wanted to have a draft Brexit agreement for the cabinet to approve at a special meeting on Monday or at its regular meeting on Tuesday. It is not clear this weekend that a form of words will be ready in time.

If it is not, the timetable might slip again. It would then be too late for a European Union leaders’ summit at the end of this month, so we would fall back to the scheduled summit on 13 and 14 December. This would leave a week for the “meaningful vote” before the House of Commons rises for the Christmas recess on 20 December.

By then, there would be little margin for error before the European parliament begins its time-consuming procedure to ratify the withdrawal agreement. No wonder cabinet ministers, civil servants and EU negotiators are alarmed by the prospect of a no-deal scenario coming about by accident.

Even if you have heard it all before and do not want to read another word about backstops, Mr Johnson is not sounding a false alarm. We really are close to the moment when the House of Commons is going to have to step up to its moment of national destiny and decide the country’s future.

It might be asked why Mr Johnson chose Friday to announce his resignation. It might make more sense to wait until we know what the deal looks like, or that there is not going to be an agreement. But he is trying to focus the minds of his fellow MPs on the nature of the decision before them.

And, above all, he is performing a valuable service to the national village by reminding us that the options are not limited to those presented by Theresa May. The choices are not just deal or no deal. There is also the option of going back to the British people to check that the deal is what they want, or, in the event of a no-deal scenario, that they are prepared to leave the EU without a deal.

In the next few weeks MPs – all of them, of all parties, and frontbenchers as well as backbenchers – need to consider deeply the arguments Mr Johnson made. “Given that the reality of Brexit has turned out to be so far from what was once promised, the democratic thing to do is to give the public the final say,” Mr Johnson said. “This would not be about rerunning the 2016 referendum, but about asking people whether they want to go ahead with Brexit now that we know the deal that is actually available to us, whether we should leave without any deal at all or whether people on balance would rather stick with the deal we already have inside the European Union.”

And not just the arguments made by the younger Mr Johnson. What was striking about his resignation was the support for it from his brother Boris. If other hard Brexiters agree with Boris Johnson that the prime minister’s plan for Brexit is “substantially worse than the status quo”, then the numbers in the House of Commons for a final say referendum start to look rather different.

It is time for MPs to pay attention and listen to the brothers Johnson, the boys who cried wolf.