We all pass certain milestones in our lives that cause us to stop and reflect. The death of a parent; a child finishing school; one's former tutorial partner becoming the prime minister. Your humble Undercover Economist is having to deal with all three in the space of a few months.

I don't remember much about Liz Truss from studying mathematical logic alongside her at Oxford. I was too busy wrestling with Peano's axioms; I suspect she felt the same. And I doubt she trembled to read the recent revelation in The Economist that, while the Conservative grassroots venerate her, the Liberal Democrats are targeting "the Tim Harford voter". Truly, the narrative arc of my life story has taken a disturbing twist.