S eventy years ago, the British government recognised that smoking caused lung cancer, thanks to a breakthrough in medical science. In an interview to mark the anniversary, Sir Richard Peto, a pioneer in this area, highlighted one way in which the discovery was significant. It led, he said, to a boost for public health comparable with 19th-century improvements in sewerage and water quality.

The shift in attitudes to smoking did not happen suddenly. The tobacco and vapes bill championed by Rishi Sunak, which fell when he called an election , was the culmination of a decades-long process. If the law is resurrected by the next government – as seems likely given the inclusion of similar measures in Labour’s manifesto – it will become illegal to sell tobacco to anyone born since 2009, and vapes will be more tightly controlled.

It seems extraordinary now, but millions of people did not accept that smoking was harmful as late as the 1990s. Sir Richard said that smokers “didn’t emotionally believe it” – so invested were they in their habit, and unwilling to think that the government would allow a dangerous product to be advertised. For decades, the UK government (along with others) opted for voluntary agreements in preference to laws.

In one extraordinary episode, Philip Morris, the tobacco company, took out an injunction against Thames TV, because it objected to a documentary using footage of cowboys with lung disease to challenge the “Marlboro man” image. Between .