When I was a boy, maybe five-six years old, I stumbled in the school playground, fell and scraped my fingers. There was blood. A best friend was astonished: “You don’t bleed black?” he asked.

I’ve always dismissed this as an innocent child’s question, for in 1960s England, I was the odd boy out in our Grimsby school in the Midlands, where my father treated pulmonary diseases in coal-mining families. But it got stranger when, as a seven-year-old, I returned to north Bihar. We lived with my maternal grandparents near the railway line approaching Muzaffarpur junction, and I was warned not to mix with the boys who played along the tracks. Still, I received a severe scolding and was made to bathe after a cousin once alleged: “He touched a Dom.” The Dom is a Dalit, a scavenger, who removes carcasses. For the privileged, the Dom was also a joke: the exclusive Don Bosco School in Patna was called “Dom ka Boss” school.