In many countries, prisons are almost a by-word for smoking. It is embedded in prison systems, part of their subcultures and special vocabularies. In Britain, for example, tobacco is “snout” and those who illicitly trade in it are “barons”. The thought of being able to stub out smoking in prisons has normally been regarded as little more than a pipedream.

All credit, then, to the prison authorities in California, the largest and most diverse US state, which now allows no tobacco at all on state property. No employee, visitor or inmate is exempted. With 33 prisons and 170 000 prisoners, seven out of 10 of whom are smokers, this is an extraordinary achievement, …