Again, I suppose I was grateful not to be smacked in the face by someone who felt “disrespected” (that is, not adequately feared). And I’m sure that many of the others there simply didn’t understand me; at this one bus stop there was a mixture of Asian, eastern European and African voices. There can be little sense of communal spirit if you feel that you don’t know your neighbour, that you can take nothing for granted in common; if, in fact, you can no longer even be sure that you speak the same language. This way does peer pressure die.

That same week, back on the train, language reared its head. A well-dressed, well-built man in his thirties was standing in an averagely crowded carriage, booming into his mobile phone in a sub-­Saharan language. People caught each other’s eyes and looked away. I got up and approached him.

“Could you keep it down just a little please?” I asked, motioning a lowering effect with my hand. He glared straight at me as though weighing me up, but then did indeed bring the volume down a notch. But my action proved too much for one down-at-heel, middle-aged white man standing nearby. “Leave him alone,” he called to me. And then to the man on the phone: “You do what you want, mate.”