On 12 June, a chastened Theresa May appeared before the Conservative backbench 1922 committee. "I’ll serve as long as you want me," May told Tory MPs. That was an acknowledgment that she was in office but no longer in power and that, having squandered the Conservatives' first majority for 23 years, she would never be let near a general election campaign again. Unlike Labour, as a former Cameron aide once told me, the Tory party is an "unsentimental creature".

But asked about her future by reporters during her Japan trip, May declared that she was "not a quitter" and even that she would fight the 2022 general election ("Yes. I'm in this for the long term.") What's changed? Well, as May once remarked: "nothing has changed".

The Prime Minister will not fight the next general election and she continues to serve at her party's mercy. But, after reports that she intends to depart in August 2019, May has avoided placing a expiry date on her premiership (in what Tory sources suggest was a snap response to a snap question) To do otherwise, as Tony Blair learned to his cost, would risk further eroding her depleted authority (though her incredible pledge has merely done the same).

May is a political zombie but for the Tories she is a useful one. At present, the party has no pre-eminent alternative leader: Boris Johnson is an unfunny joke, David Davis is Brexit-beaten, Amber Rudd has a minute majority (376 votes) and Philip Hammond is loathed by Leavers. Last summer, May became Conservative leader as the candidate most MPs could live with. This broad but shallow support similarly sustains her now.

The Prime Minister, a "reluctant Remainer", has also become, as one Tory MP told me, "the guardian of hard Brexit". The party's dominant Brexiteer wing fears that a change of leader would mean a change in position. In the view of some MPs, May is a human sponge who can absorb the political pain of Brexit and nurture younger Tory talent (Tom Tugendhat, Johnny Mercer and James Cleverly).

All of this explains why there has be no challenge to May's position and why she may yet lead the country through Brexit. But the fundamentals have not changed. After May lost her majority against Labour, the Tories have no intention of discovering whether she can go one worse and lose altogether. Against Jeremy Corbyn, a man who Conservatives sincerely believe would destroy the British economy, the Conservatives intend to deploy their best weapon.

As several senior Tory MPs have already signalled this morning, that is not Theresa May. "I think it’s going to be difficult for Theresa May to lead us into the next general election," former education secretary Nicky Morgan remarked with British understatement. Another former minister put it more bluntly to me: "There is not a hope in hell that she will lead us".

May will only remain prime minister as long as her party believes the benefits outweigh the costs. Should the calculation change, her downfall will be swift. Conservative leaders are easier to remove than Labour ones, owing to the former’s regicidal nature and less protective rules. Only 48 Tory MPs (15 per cent) are required to trigger a confidence vote in a leader, who must resign if defeated. The rebels need only submit private letters to Graham Brady, the chair of the 1922 committee, and are guaranteed anonymity.

As May well knows, the Tories have not lost their capacity for regicide. The Prime Minister, unlike Margaret Thatcher (who declared in 1987: "Yes, I hope to go on and on") and Tony Blair (who vowed to serve a "full third term" in September 2004), does not mean what she says. May dreamt of winning her party's first landslide majority for 30 years and ended up without one at all. The Tories have no intention of allowing a gorier sequel.