Veteran journalist Robert Fisk went to Syria to investigate the alleged "chemical attack" in Douma and found a local doctor telling him the people seen struggling to breathe were suffering not because of a "chemical attack," but because of oxygen starvation as a result of a dust storm blowing dust into the underground "rubbish-filled tunnels and basements in which they lived."

This is the story of a town called Douma, a ravaged, stinking place of smashed apartment blocks – and of an underground clinic whose images of suffering allowed three of the Western world's most powerful nations to bomb Syria last week. There's even a friendly doctor in a green coat who, when I track him down in the very same clinic, cheerfully tells me that the "gas" videotape which horrified the world – despite all the doubters – is perfectly genuine.