The response from the US, UK and France to a briefing on Thursday at the Organisation for the Prohibition of Chemical Weapons (OPCW) in the Hague was perverse, to say the least. Russia had brought 17 witnesses from Douma who stated that there had been no chemical weapons attack there earlier this month – the pretext for an illegal air strike on Syria by the three western states.

The witnesses, a mix of victims and the doctors who treated them, told accounts that confirmed a report provided last week from Douma by British reporter Robert Fisk – a report, it should be noted, that has been almost entirely blanked by the western media. According to the testimony provided at the OPCW, the victims shown in a video from the site of the alleged attack were actually suffering from the effects of inhaling dust after a bombing raid, not gas.

The first strange thing to note is that the US, UK and France boycotted the meeting, denouncing Russia for producing the witnesses and calling the event an “obscene masquerade” and “theatre”. It suggests that this trio, behaving like the proverbial three monkeys, think the testimony will disappear if they simply ignore it. They have no interest in hearing from witnesses unless they confirm the western narrative used to justify the air strikes on Syria.

Testimony from witnesses is surely a crucial part of determining what actually happened. The US, UK and France are surely obligated to listen to the witnesses first, and then seek to discredit the testimony afterwards if they think it implausible or coerced. The evidence cannot be tested and rebutted if it is not even considered.

The second is that the media are echoing this misplaced scorn for evidence. They too seem to have prejudged whether the witnesses are credible before listening to what they have to say (similar to their treatment of Fisk). Tellingly, the Guardian described these witnesses as “supposed witnesses”, not a formulation that suggests any degree of impartiality in its coverage.

Notice that when the Guardian refers to witnesses who support the UK-UK-French line, often those living under the rule of violent jihadist groups, the paper does not designate them “supposed witnesses” or assume their testimony is coerced. Why for the Guardian are some witnesses only professing to be witnesses, while others really are witnesses. The answer appears to depend on whether the testimony accords with the official western narrative. There is a word for that, and it is not “journalism”.

The third and biggest problem, however, is that neither the trio of western states nor the western media are actually contesting the claim that these “supposed witnesses” were present in Douma, and that some of them were shown in the video. Rather, the line taken by the Guardian and others is that: “The veracity [of] the statements by the Russian-selected witnesses at The Hague will be challenged, since their ability to speak truthfully is limited.”

So the question is not whether they were there, but whether they are being coerced into telling a story that undermines the official western narrative, as well as the dubious rationale for attacking Syria.

But that leaves us with another difficulty. No one, for example, appears to be doubting that Hassan Diab, a boy who testified at the hearing, is also the boy shown in the video who was supposedly gassed with a nerve agent three weeks ago. How then do we explain that he is now looking a picture of health? It is not as though the US, UK and French governments and the western media have had no time to investigate his case. He and his father have been saying for at least a week on Russian TV that there was no chemical attack.

Instead, we are getting yet more revisions to a story that was originally presented as so cut-and-dried that it justified an act of military aggression by the US, UK and France against Syria, without authorisation from the UN Security Council – in short, a war crime of the highest order.

It is worth noting the BBC’s brief account. It has suggested that Diab was there, and that he is the boy shown in the video, but that he was not a victim of a gas attack. It implies that there were two kinds of victims shown in the video taken in Douma: those who were victims of a chemical attack, and those next to them who were victims of dust inhalation.

That requires a great deal of back-peddling on the original narrative.

It is conceivable, I suppose, that there was a chemical attack on that neighbourhood of Douma, in which people like Diab assumed they had been gassed when, in fact, that they had not been, and that others close by were actually gassed. It is also conceivable that the effects of dust inhalation and gassing were so similar that the White Helmets staff mistakenly filmed the “wrong victims”, highlighting those like Diab who had not been gassed. And it is also conceivable, I guess, that Diab and his family now feel the need to lie under Russian pressure about there not being a gas attack, even though their account would, according to this revised narrative, actually accord with their experience of what happened.

But even if each of these scenarios is conceivable on its own, how plausible are they when taken together. Those of us who have preferred to avoid a rush to judgment until there was actual evidence of a chemical weapons attack have been invariably dismissed as “conspiracy theorists”. But who is really proposing the more fanciful conspiracy here: those wanting evidence, or those creating an elaborate series of revisions to maintain the credibility of their original story?

If there is one thing certain in all of this, it is that the video produced as cast-iron evidence of a chemical weapons attack has turned out to be nothing of the sort.