That was before the atrocities of the Second World War, during which the Luftwaffe brought the terror of the Blitz to London, and Allied bombers killed hundreds of thousands of German civilians in Berlin, Hamburg and Dresden. It was before the atomic bombs dropped on Hiroshima and Nagasaki heralded a world in which whole cities could be destroyed by the press of a button.

So, after the Germans and Japanese surrendered, a debate began about whether the military results outweighed the human cost of indiscriminate bombing, and some said that the British and American attacks of 1944 and 1945 deserved to be classed as “war crimes”. Though strategic bombing was still used in subsequent conflicts such as the Vietnam War, a growing revulsion led, in 1977, to a protocol being added to the fourth Geneva convention. This outlawed civilian bombing.

In recent years, beginning with the First Gulf War, strategic bombing campaigns have used much more precise weaponry. Now, unmanned drones directed by pilots in the Nevada desert can strike targets in the mountains in Afghanistan. But though these are getting ever more accurate, they still kill many more civilians than they do militants, and the question of whether they should be allowed continues to be asked.