He must go. Boris Johnson should never have been allowed anywhere near power. His long and well documented track record of dishonesty and poor character should have effectively disbarred him from public office.

His election remains a stain on the UK in general and the Conservative party in particular.

Why? Because liars corrode democracy.

Last week British politics hit what must be its low of the internet age. Thanks to one of Mr Johnson’s lies. The prime minister falsely accused the leader of the opposition, when he was director of public prosecutions, of failing to pursue the country’s most notorious sex offender, Jimmy Savile.

It was, by any measure, an appalling smear. Sir Keir Starmer, the now Labour leader, had nothing to do with the case.

READ MORE: Boris Johnson under pressure for Savile remarks after Keir Starmer ambushed by mob

This was – to use a much-abused technical term – disinformation. And it has already had consequences. Last night Sir Keir and colleagues were mobbed by – supposedly – anti-vaccine extremists.

Widely shared videos show “protestors” screaming various slogans typical of the victims – and perpetrators – of online conspiracism. Sir Keir was asked what it was like to work for the New World Order, a core internet-grade conspiracy theory, with strong anti-semitic overtones, of a ruling global cabal.

And, chillingly, they yelled another word too: Savile.

If you do not routinely wade in the cesspit of online extremism it is hard to make sense of all of this. But go to an anti-vax protest – as I have – or trawl though the internet and you will quickly encounter people who believe in one strain or another of a conspiracy theory that the world is run by gangs of predatory paedophiles. This is the heart, for example, of America’s Q-Anon movement. It is routine among hardline anti-lockdown, anti-vax campaigners.

So when Mr Johnson lashed out with the Savile disinformation, he was effectively putting a target on Sir Keir. Would internet bams have mobbed the Labour leader regardless of what Mr Johnson said. Sadly, probably. But this nevertheless was a remarkable, ugly and dangerous episode. Because those spraying their spittle at Sir Keir now think they are dealing with a paedophile protector, and have the word of the prime minister to support this.

There have to be consequences for Mr Johnson. He cannot be allowed to stay in power.

Continuing to enable a man of Mr Johnson’s calibre is endangering politics.

This may sound like hyperbole. But we only need to look across the Atlantic to see just how dangerous targeted disinformation can be.

So, Tories, don’t dally-dally with democracy. Dump him now.

However, ousting one liar is not going to be enough. We need to build resilience across our politics to lies.

One of the most disheartening sights in this whole saga was seeing the disinformation minister – under questioning from SNP MP John Nicolson – refuse to denounce his boss.

We need to build political parties which can protect themselves from people like Mr Johnson. How? Well, they can start with meaningful counter-disinformation training. The UK Government itself has developed a useful toolkit called Resist 2 to help civil servants – and anybody really – spot disinformation and misinformation. Surely it is time for politicians to go back to school?

There are respectable Conservatives who are committed to supporting reality-based discourse, especially abroad. So we have strong resources for countering falsehoods about, say, Ukraine. Let us apply these same principles to UK politics.

Scotland has proven relatively resilient to disinformation. Our vaccine uptakes are high. One of the more notorious of Vladimir Putin’s propaganda outfits recently quit the country, citing a hostile environment. Two parties led by Kremlin TV personalities ran in last year’s Holyrood election – but were unable to get any candidates elected.

This sounds good. But we cannot afford to be complacent. Already we are seeing even the word “disinformation” being irresponsibly politicised, weaponised, and not just by the usual online dingdongs.

Take the last week or two. Nationalists and unionists – neither covering themselves in huge glory – have crossed swords about state pensions. They each have very different perspectives about whether there would be an ongoing UK liability after independence to people who have paid British stamp. Writing in The Herald, independent scholars from the Fraser of Allander Institute described the row as “both more complex and more uncertain than either ‘side’ might claim”. Yet right now commentators are accusing their opponents of disinformation, of lying. This is very disappointing conduct. Bluntly, it suggests an urgent need for training among Scottish apparatchiks, operatives and politicians themselves in what disinformation actually means.

It is not just another stupid buzzword for “something with which I disagree”.

So Mr Johnson must go. But that alone will not be enough to fix our politics.