“As Prime Minister, I am not prepared to delay Brexit any further than 30 June,” Theresa May, Hansard, March 20.

By the time the Prime Minister said these words, in answer to a question from Pete Wishart at Prime Minister’s Questions, it was very late in the day for her.  A week earlier on March 13, the Commons had voted down the Withdrawal Agreement for the second time.  75 Conservative MPs had opposed it in the lobbiesThat week also saw the passing of the Spelman amendment “to take no deal off the table”, and the announcement of a forthcoming vote on extension. Anthony Wells’ YouGov table of opinion polls confirms that the Conservatives have not polled above 40 per cent since it ended.

But let us now imagine that, after the EU rebuffed May’s date on April 11, thereby necessitating next week European elections, she had balked at their alternative of October 31.  You will say that the Commons would not have tolerated a No Deal alternative – as it had indicated by passing a statutory instrument on March 27 that took the March 29 exit date out of legislation.  And you are almost certainly right.

However, she could have gone to that lectern outside Downing Street, and said roughly the following: “I told the Commons a few weeks ago that I was “not prepared to delay Brexit any further than 30 June”.  I also said that a consequence of such delay – elections to the European Parliament in Britain – would be unacceptable.”

“Here are my precise words from Hansard on the same day: ‘the idea that three years after voting to leave the EU, the people of this country should be asked to elect a new set of MEPs is, I believe, unacceptable. It would be a failure to deliver on the referendum decision that this House said it would honour’.”

“I believe that politicians should keep their word, and I am therefore resigning as Leader of the Conservative Party.  The Party will now hold a leadership election to replace me, and I expect a new Prime Minister to be in place by the beginning of this summer’s Parliamentary recess.”

Now such an announcement would neither have met the June deadline nor prevented the Euro-elections.  But it might have persuaded a section of disillusioned voters that, although Brexit had not been delivered on time, at least one politician keeps her promises.  The Iraq War, the expenses scandal, the economic crash: all have, over a span of over 15 years, helped further to lower trust in the system.

As we write, May’s failure to keep her word looks like an addition to that list.  She promised that Brexit would take place March 29 over a hundred times.  It didn’t happen.  She said then she was not prepared to delay it further than June 30.  That end-date won’t happen, either.  Extension ends on October 31.  And she said that elections to the European Parliament would be “unacceptable”.  Then she accepted them.

The point is really very simple.  Voters don’t follow the ins and outs of Brexit – indicative votes, customs arrangements, John Bercow’s rulings, and all that – but they have an unerring nose for smelling out politicians.  The Prime Minister promised that we would leave on March 29 and we didn’t, they think.  Ergo, we won’t vote for her.  So two possible futures for the Conservatives now open up.

The first is that it is too late for a new leader.  May’s stubborness in bringing back her deal for a third time; her refusal to face up to the Commons’ rejection of it; the attempt that has followed to strike a deal with a man she rightly denounces elsewhere as a menace to freedom – all that has poisoned the well for any successor.  The week of March 15 was an ERM moment.

The second is that modern politics is extraordinary volatile.  Consider the rise and fall of UKIP, the overthrow of David Cameron, Jeremy Corbyn’s 2017 election performance.  So a new Conservative leader could turn events round, though he or she might well have to come from outside the Prime Minister’s Government altogether, and force an election sooner rather than later.

The first could be right.  But the Conservative Party cannot presume so – and simply hand the future over to Corbyn and Nigel Farage.  It has to work on the basis that the second might hold.  It follows that the longer May remains Prime Minister, the deeper the damage to the Party and the country.

The 1922 Committee’s executive has a big decision to make this week.  On Thursday, it will meet May to seek to extract a date for her depature.  It should not be sentimental.  Her hanging on might be attributed to a sense of duty.  But to borrow the language that Robert Halfon used on this site last week, it is utterly selfish.  Prime Ministers want to leave a legacy behind them.  May clearly sees hers as the Withdrawal Agreement.  But the Commons will not pass it as it stands.

It might do so, with or without Corbyn’s formal cooperation, were MPs to tack Customs Union membership on to it.  But such a decision would force yet more resignations, were May to support it, and split the Conservative Party in half.  However unpalatable it may be, the Committee must, if she refuses this week to go by the end of the summer, change the leadership challenge rules immediately – perhaps with a trigger ballot threshold of 40 per cent or so.  We are well aware that the most painless course for them is to opt for mañana.  But the wait for tomorrow risks marginalisation – even oblivion.