To that fundamental theorem of arithmetic, first recorded by Euclid in 300BC, we can now add the ERG formula. It states that if any number is attached to a claim made by members of the pro-Brexit European Research Group of Tory MPs, it should be adjusted for reality and cut in half.

This week, when Tory rebels were confident they had submitted the 48 letters necessary to trigger a vote of confidence in the prime minister, it turned out, pitifully, to be only half that. Cue amusement.

Brexiteers were revealed as a bunch of bungling assassins. “It was very stupid,” says a former minister. “Would have been far better to wait a few weeks for May’s deal to fail. I tried to tell them.