Daniel Hannan is an MEP for South-East England, and a journalist, author and broadcaster. His most recent book is What Next: How to Get the Best from Brexit.

Imagine the sense of disappointment at The Guardian. A Greenpeace undercover team goes to a great deal of trouble to set up a sting operation on the free-market Institute of Economic Affairs. The IEA’s director, Mark Littlewood, is surreptitiously filmed talking to a supposed potential donor. Ah, now this should be good: what does the capitalist pig say in private?

Annoyingly, Littlewood makes clear that donors don’t get to tell the IEA what to write. His institute, he explains, has principles that it has been pushing since the 1950s. Anyone who wants to support those principles is welcome to give money; but it won’t be accepted with strings attached.

Hmm. Awkward. That’s pretty much the opposite of corruption. So what to do? Junk the whole investigation? Admit that even ghastly neoliberals have convictions and that they stick to them? Of course not. Far better to run the piece anyway in a “wow just wow” tone. Include some wobbly camera angles: that generally does the trick. I mean, it’s secret filming. It’s secret filming!

Maybe I’m being rosily nostalgic here, but I don’t believe such a piece would have run ten years ago. The Guardian used to be my daily paper in the days when people got their news in printed form. I liked its size; I liked its early adoption of newsprint that didn’t stain your hands; I liked the G2 section. True, the comment pages could be insufferably self-righteous, and their tone sometimes seeped into the news coverage. But, although it was rarely objective, the paper did at least set out to be accurate. It’s hard to imagine that, in Alan Rusbridger’s day, there’d have been a story based on the premise that the only way to get a free-market think-tank to accept your donation was to pretend to be a free-marketeer yourself.

Falling circulation and competition from online outlets that blur the line between news and comment are making a lot of newspapers more clickbaity – or, at least, readier to play to their readers’ prejudices. In this case, “prejudices” is precisely the word. Most people’s notion of “corruption” overlaps heavily with their concept of “things I happen not to like”. The way the IEA story was run in Leftist media last week more or less depended on the assumption that promoting free-market ideas was intrinsically disreputable.

Here’s a rule of thumb: no one asking a think-tank who its donors are is interested in the answer. The question is not meant to elicit information, but to delegitimise. These libertarians, we are invited to believe, are corporate shills, doing the bidding of sinister industrialists and financiers.

Just stop and think, for a moment, about the what is being alleged. All those eager young people working at the IEA, the Adam Smith Institute, the Centre for Policy Studies, and the TaxPayers’ Alliance – almost all of them on lower salaries than they could get elsewhere – are supposed to be part of a conspiracy. They don’t really believe in small government. They’re just saying what they’re paid to say.

The suggestion is too preposterous to merit serious refutation. Never mind that big corporates generally dislike free-marketeers, preferring cosy deals with governments to open competition. The Greenpeace/Guardian sting depends on the idea that, if we weren’t somehow being bought, none of us would be on the Right at all.

I’m pretty sure Guardian editors know that this is bunkum; but they also know that a fair number of their readers will lap it up. A lot of people genuinely struggle with the idea that someone might disagree with them other than from base motives. This tendency exists on the Right as well as on the Left, but there is an asymmetry. Because the assumptions that infuse our public discourse – comedy shows, TV dramas, pop lyrics and so on – tend to be Left-of-centre, most conservatives eventually get the hang of what makes the other side tick; but the reverse is not always true. If you rarely hear Tories explaining what they think, you can easily settle into comfortable assumptions about what heartless swine they are.

Correcting people’s prejudices is laborious and, in terms of online traffic, unrewarding. So, increasingly, newspapers pander to it. Look, for example, at the deranged speculations that appear week after week under Carole Cadwalladr’s byline in The Observer. In her determination to show that Brexit is some sort of criminal enterprise funded by the Kremlin, she repeatedly uses the language of online conspiracy theorists: “secret club of people who rule Britain”, “shadowy global operation”, “dark money” etc. Several Observer journalists are embarrassed to see their paper giving space to this sort of nonsense. But there is a large constituency of people who simply cannot bring themselves to accept the 2016 referendum result, and are in the market for any story, however loopy, that seems to invalidate it. It’s the modern version of H.L.Mencken’s aphorism about no newspaper going broke by underestimating its readers.

We’re often told that blogs and social media push people into political silos, making them less likely to engage with other opinions. But the old media are, if anything, even more guilty, though they manage to maintain a self-righteous tone while doing it.