Nothing has changed. That was the message from MPs when they emerged at the end of Wednesday evening’s meeting of the 1922 Committee.

What an anticlimax. The rules for a leadership challenge remain unchanged. She will campaign as normal in the European elections, and cannot see Sir Graham Brady, the Chairman of the ’22, until Friday.

And yet everything has changed. The backbenchers who milled about in the hot, high the Committee Corridor while the Executive of the ’22 decided what to do, or what not to do, have decided she must go.

“The worst Prime Minister ever,” one of them said, and when ConHome raised pedantic historical objections, went on to complain that she does not take in advice even when it would clearly be to her advantage to absorb it.

“She’s taken the phone off the hook and is hiding under the bed,” another backbencher said with a contemptuous laugh.

Earlier in the afternoon, the dreaded Pizza Club of Cabinet ministers was said to have decided she must go. But then she was said to have refused to see the Pizza Club, even if they came in one by one, or slice by slice.

There was nevertheless a tremendous buzz of excitement. For those not centrally involved in the crisis it was all very enjoyable.

“Has David Mundell done for her?” ConHome wondered, trying to stand up one of the prevailing rumours.

“I think he has,” a close observer said. “He spoke last night to Ruth Davidson.”

Within seconds a highly plausible though not necessarily correct and certainly not complete account of what has happened was pieced together. It looked as if it was the Haggis Club which had administered the fatal blow.

The Prime Minister was found to have given ground on the second referendum in her Withdrawal Agreement Bill, to be published on Friday. This appalled Davidson, for if the Government concedes there can be a second referendum on Brexit, what objection can it have to a second referendum on Scottish independence?

Speculation raced ahead of fact. Theresa May is plainly finished. Who will be Davidson’s candidate for the leadership?

“Michael Gove,” a close observer said. “He understands things north of the border. There’s his campaign manager over there.”

“I know nothing,” an MP said with the smile of one who wishes it to be understood that he knows a lot, and probably does.

“You’ll have to write an extra chapter of your book,” several people said, referring to your correspondent’s life of Boris Johnson.

One of the reasons why Tory leadership campaigns are so exciting is that they are completely unpredictable, unless you have inside information which happens to be the inside information needed to work out who is going to win the race.

In 1963, the disregarded figure of Selwyn Lloyd was working hard to make the 14th Earl of Home the next leader at a stage when most other people still quite reasonably assumed Harold Macmillan’s successor was going to be a member of the House of Commons rather than a hereditary peer.

Another reason why Tory leadership campaigns are so exciting is that backbenchers who feel their talents have been overlooked for the last ten, 20 years or even 30 years suddenly feel that if their man or woman wins, they will have a last chance of happiness, or at least a last chance of junior ministerial office.

The temptation, in these circumstances, to swear undying loyalty to half a dozen candidates is considerable. That is one reason why the race becomes so difficult to read.

There is probably some Selwyn Lloyd figure who is even now recruiting key figures to the Stop Boris campaign, which in turn may or may not manage to stop him.

Meanwhile, May is still Prime Minister, but on the understanding, at least among her backbenchers, that on Friday she will tell Sir Graham she will go without any need for a change in the rules.

“Leadsom’s quit!” a colleague exclaimed. It is not the resignation which Tory backbenchers were keenest to see, but it makes the end of May’s prime ministership even more certain.