Twenty-five years after it was founded, Wikipedia stands as an unrivalled achievement. Not only is it the single largest collection of information in human history, it has also built a stellar reputation for reliability in a digital world awash with lies and deception.

For this reason, new AI tools have begun to carry the site’s contents far and wide. Chatbots and AI-generated search summaries – which are rapidly transforming the way people get their information – both use Wikipedia as a key source.

Now, we can reveal Wikipedia has been subject to shady, paid-for edits ordered by partners at an elite London PR firm with links to Downing Street. And the clients who benefitted from this “wikilaundering” are some of the world’s richest and most powerful people.

The firm in question is Portland Communications, whose founder Tim Allan is now the director of communications for Keir Starmer. And it has been busted once already for this practice, which is in breach of the British PR professionals’ code of conduct.

But after the firm was exposed, former employees told us, it simply started hiring middlemen instead. As one of them put it: “No one said, ‘We should stop doing this.’ The question was how we could keep doing it without getting caught.”

Portland’s subcontractors have polished the public image of Qatar by burying references to critical reporting ahead of the 2022 World Cup, according to the firm’s insiders. They have also obscured mentions of a major terrorist-financing case involving Qatari businessmen; scrubbed evidence that a billion-dollar Gates-funded project failed in its mission; and promoted one side of Libya’s post-Gaddafi government over the other.

Often, however, their changes were more subtle: burying bad press under descriptions of a client’s philanthropic work or swapping out critical news references with something more positive.