Shortly after Boris Johnson left university, he wrote a short essay on the art of winning election to the Oxford Union. One of the bits of advice he gave was never to trust anyone else's numbers: "I knew one hack who claimed to control 50 votes. I doubt he controlled five."

It's a useful rule of thumb in real politics, too. So when Grant Shapps, outed in the Times as the man behind the plot to oust Theresa May, tells the BBC he has collected the names of "more than two-dozen, perhaps up to 30", it's safe to assume that the actual number is closer to two-dozen than 30. In any case, he is short of the 48 names needed to clear the 15 per cent threshold for a vote of no confidence in May as Conservative leader.

Many of the rebel MPs believe that the Tory whips are the ones who leaked Shapps' name to the Times, in order to smoke him out. The gamble is that in revealing that he doesn't have 48 MPs yet it encourages some of the already dissenting to quietly return to the fold – but the risk is that it means those on the fence decide it's now or never.

Which of these possibilities will happen is anyone's guess. It could be that the planned Monday ultimatum by disgruntled MPs fizzles out, and it could be that it catches fire. A lot hinges on what happens over the weekend, not only in Conservative WhatsApp groups, but on the Sunday shows and crucially the reaction to the PM in the country.

In my New Statesman column, I wrote about the fragile equilibrium at the heart of the Conservative Party. That balance was tilted a little by Theresa May's lacklustre speech. A bad poll or headline in the Sunday papers could yet tip it up entirely.