And yet, for decades, every law proposed in Parliament to curb smoke emissions was watered down so heavily that it had no tangible effect. What explains such legislative inertia?

Vested interests were a major obstruction. In 19th- and 20th-century London, many industries thwarted attempts by successive governments to clean up the capital’s air. Often they would simply refuse to install smoke purifiers on their factory chimneys, blaming the smoke from household fires instead.

Moreover, the fines on violators were often so small that they could not serve as a deterrent. Magistrates had sympathy for the industrialists, especially the smaller ones, who could not afford to convert their furnaces to more efficient, cleaner models. And, above all, smoke from industrial chimneys represented jobs and growth — which, in turn, gave people wages with which they could afford a fire at home, thus exacerbating the problem.

There was a cultural component, too. The British were wedded to their open fires. Closed stoves, popular throughout much of Europe, especially in Germany, were shunned by Londoners. During World War I, Britons were exhorted, in the words of the famous song, to “keep the home fires burning.” Politicians were simply not willing to risk unpopularity by forcing Londoners to stop using coal and go over to gas or electric heating instead. In Britain today, in an echo of these earlier concerns, the government is cutting subsidies for onshore wind and solar farms, anxious not to offend voters in rural areas where such facilities would be built.

It took a disaster to force London to change direction. In 1952, a “great killer fog” lasted five days and killed an estimated 4,000 people. In a Britain trying to turn a corner after the death and destruction of the Blitz, this was unacceptable. A Clean Air Act was passed in 1956, forcing Londoners to burn smokeless fuel or switch to gas or electricity, power sources that had become much cheaper as these industries expanded.

Legislation for clean air was taken up by many politicians, but perhaps the most surprising was the extravagantly mustachioed Conservative politician Sir Gerald Nabarro, whose flamboyantly expressed opinions included the retention of capital punishment, opposition to European integration and strident racism. But it was Nabarro who sponsored the 1956 act.

More surprisingly still, it was Robert Maxwell, the Czechoslovakian-born British media mogul and Labour member of Parliament, who pushed through further legislation in 1968 to strengthen the provisions of the previous bill. His dubious financial transactions may have earned him the nickname “the bouncing Czech,” but in this instance he performed a genuine public service.