Every few weeks, it seems, Carole Cadwalladr drops a long piece for the Guardian or the Observer about how the Trump and Brexit campaigns mind-hacked democracy. On both sides of the Atlantic, people who don’t like Trump or Brexit share these pieces and shriek.

The latest article, which lit up the political internet at the weekend, has the added spice of a whistleblower – a pink-haired ‘data science nerd’ straight out of science-nerd central casting. He’s called Christopher Wylie and Cadwalladr reveals that he has been the source for her much-vaunted scoops on Cambridge Analytica, the data firm who worked with the Trump and Brexit campaigns. Now he’s ready to go on the record about his work at Cambridge Analytica – or how, as he puts it, he became “Steve Bannon’s psychological warfare mindfuck tool”

It’s sexy stuff; the characters feel like a movie. You have bad guys – Trump, Bannon, the sinister billionaire IT-man Robert Mercer. The trouble is, the plot is already all too familiar. Anybody who has been paying attention knows that political campaigns have used people’s private data, harvested from Facebook, for a long time now. As businesses do to consumers, campaigns employ sophisticated ‘psychological profiling’ techniques to sway gullible parts of the electorate.

The more interesting – though less Hollywood – accusation about Cambridge Analytica is that, far from being masters of the new data universe, they are British ‘snake oil salesman’ who essentially repackaged and flogged well-established techniques to a desperate Trump campaign, as Paul Wood reported so brilliantly for The Spectator here.

The chief reveal in the Observer’s latest is confirmation of what’s been known for almost two years, which is that Cambridge Analytica may have breached the terms of Facebook’s agreement. They may have used Facebook’s data under false pretences. They may also have claimed to have deleted Facebook data when they didn’t, as the whistleblower alleges. Cambridge Analytica dispute this.

The true horror, of course, is not that sinister right-wing forces can use information people share on social media to, as Wiley puts it, ‘mindfuck’ electorates. It’s that Facebook has all this powerful information in the first place. And what’s odd is that people don’t seem to mind data being plundered if the beneficiaries are the perceived good guys.

Barack Obama’s 2012 campaign, for instance, used one of Facebook’s APIs (application programming interfaces) and data to target voters. It’s clever and complicated, but what it boils down to is that Obama’s data scientists were able to persuade about a million Facebook users to connect their profile to the Obama campaign website. They were then able to access the profiles of these people, which also showed who their friends were. From this they were able to construct real life social networks, which enabled them to target many, many more potential Obama voters. “If you log in with Facebook, now the campaign has connected you to all your relationships,’ boasted a digital campaign organiser.

Facebook shut down that particular API function in 2014, apparently for privacy reasons – although sceptics point out that they realised outside companies could use Facebook’s API to replicate the ‘social graph’ that Facebook makes all its advertising money from.

What Cambridge Analytica did, in essence, was the same as the Obama campaign in 2012 – though they had a smaller sample group of 250,000 to model from.

The vital difference is that Facebook didn’t officially permit CA to use its data and API in 2016. It’s possible that CA employed brilliant Russian ‘psychographics’ to connect friendships in different ways. But data experts say that the psychological profiling techniques are not actually all that successful. The essential device – and the most electorally useful one – is the use of a social media group to model and target a much, much bigger one through social media. And the essential point is that when Obama did it, such practices were written up in glowing terms. His campaign’s social media tactics were widely lauded for harvesting ‘the power of friendship’. But when Trump or Brexit do it, apparently, it’s evil.