It now seems Boris Johnson lied in regard to what he was told about the chemical agent used in the Salisbury attack. Speaking to international media only a few weeks ago he said Porton Down – the government’s leading chemical weapons facility – had been “absolutely categorical” about the providence of the weapon, saying “there’s no doubt” it had been produced in Russia.

As of Tuesday, we know Porton Down doesn’t hold that view. Gary Aitkenhead, the chief executive of the Defence Science and Technology Laboratory – the organisation operating at the government site – told Sky News this week that the precise source had, in fact, not been identified.

This is important because while it is more than possible the agent used was manufactured in Russia and deployed by the Russian state, the basis of the argument used by the government has been revealed as demonstrably false. Previously they claimed forensic evidence showed almost certain Kremlin involvement. Now they are saying it is intelligence which has led them to such a conclusion. Labour’s Diane Abbott has said Boris Johnson misled the public. This appears incontrovertible.

Then there’s the issue of a deleted tweet published on the Foreign and Commonwealth Office (FCO) account on 22 March. There too it was claimed Porton Down specialists had concluded the agent was of Russian origin. The source for that tweet was a speech given by Dr Laurence Bristow, Britain’s ambassador to the Russian Federation.

For now the FCO is saying the tweet was an error and, because it was composed in ‘real time’, “did not accurately report our ambassador’s words.”

Except it did. We know this because there is a video of Dr Bristow giving the speech where he details the same claims made by the foreign secretary to Deutsche Welle. In it Bristow clearly states there is “no doubt that this Novichok was produced in Russia by the Russian state”.

At the time Craig Murray – blogger and former British ambassador to Uzbekistan – wrote that an FCO source told him scientists at Porton Down were “unable to identify the nerve agent as being of Russian manufacture”, and were “resentful of the pressure being placed on them to do so”. Despite responses of ‘fake news’ across much of the establishment media, it now seems he was correct.

Importantly, Murray also wrote how the FCO was happy to have persuaded Johnson to at least allow the Organisation for the Prohibition of Chemical Weapons (OPCW) to investigate a sample and independently confirm the government’s findings. That may have proved decisive in giving Porton Down the licence to be honest with Sky News yesterday.

So here is what we know. The government of the day, just like with Iraq, based its pronouncements on what it wanted to find rather than actual evidence. The Foreign Office, just as with the pressure it faced to sign off on the Iraq “dodgy dossier”, was seemingly strong-armed – as were scientists at a government facility. In alliance with an obsequious, uncritical media – not to mention a cluster of Labour backbenchers – the government likely would have gotten away with it but for a combination of a functioning opposition and a fourth estate, mostly online rather than in legacy media, which pursued the truth rather than just repeating government press releases.

This brings two things into sharp relief. The first is how crucial a complicit opposition and media were to war in Iraq. Had the former done their job in a manner resembling the way Jeremy Corbyn now leads Labour, it is likely Britain would have avoided that unnecessary catastrophe. Despite an onslaught from the media to follow the government line, the opposition, in the absence of incontrovertible evidence, did not. More than being sincere to any set of particular political values, that is meant to be the opposition’s constitutional function. Whoever you vote for, Britain is safer and more prosperous for it.

The second is the historic importance of Corbyn as a politician and, more broadly, the re-emergence of the radical left as a national force. The 33 Labour MPs who signed the early day motion supporting the government – despite any actual evidence – were, until recently, those in charge of the Labour party. Again, not only is the party better off for that no longer being true, but Britain is as well.

These last several months have seen a deluge of misinformation and lies from the British establishment. Tactics reminiscent of psychological warfare, from the ‘Agent Cob’ saga to Novichok, and now right wing papers secretly recording Jews at religious events to ‘prove’ their antisemitism, have replaced anything resembling informed, impartial debate. Earlier this week when the BBC inaccurately said Jewdas – an organisation which has created materials detailing how to criticise Israel without being antisemitic – denied the existence of antisemitism in Labour altogether, it confirmed an ever-more conspicuous fact: our media has given up on the truth.

The reason why is that any party led by a politician as disruptive as Corbyn – even in opposition – is simply too much for the status quo. Given just that, the establishment will throw the kitchen sink to stop him entering 10 Downing Street. That means we are now witnessing the beginnings of a permanent suspension of a media that befits a democratic country. It is not just our government we need to hold to account, but them as well. That will matter more than ever when Labour is in government.