NOEL KING, HOST:

Facebook is banning all pages and accounts associated with QAnon, the wild, often incoherent Internet conspiracy theory, which, like many conspiracy theories, is spreading quickly. QAnon believers are now protesting coronavirus restrictions in the U.K. while cases there are rising. Here's NPR's Frank Langfitt.

MARCUS WILLIAM BIGGS: Masks don't work. Masks don't work.

FRANK LANGFITT, BYLINE: Marcus William Biggs is standing in front of London's National Gallery, a sidewalk preacher for the COVID-19 era. He says the coronavirus is really part of a worldwide conspiracy.

BIGGS: This global control mechanism which they're trying to impose on humanity to make them basically become slaves to the system and inject us all with a vaccine that basically is totally unsafe...

LANGFITT: To be clear, none of this is true. But on this day last month, thousands of people who believe COVID conspiracy theories packed Trafalgar Square to protest the threat of a second lockdown. People who study conspiracy theories here say they've never seen gatherings like this before. Like many in the square, Marcus Biggs subscribes to a core belief of the QAnon canon.

BIGGS: Satanic ritual abuse of children - they harness the energy of the child when the child is undergoing torture, and all the celebrities are taking the adrenochrome, which is taken from the adrenal gland of the children.

LANGFITT: QAnon followers believe a cabal of Satan-worshipping pedophiles runs the world and that President Trump is secretly battling them. QAnon builds on pizzagate, the debunked claim that Hillary Clinton ran a pedophile ring out of a Washington, D.C., pizza restaurant. The claim was so convincing to some that an armed man opened fire in the restaurant in 2016 during an attempt to free the nonexistent children. Nearly four years later, Biggs and others in Trafalgar Square still view pizzagate as an article of faith.

BIGGS: Pizzagate was exposed by Julian Assange. All the pedophiles were speaking to each other in this kind of cryptic language.

LANGFITT: During the pandemic, QAnon beliefs have blended with COVID misinformation and anti-vaccine distrust to form a witch's brew of conspiracy theories. For instance, some here think the coronavirus is designed to cover up child sex trafficking and that masks actually endanger your health. Marcus Biggs calls out a man who passes by wearing one.

BIGGS: Take off your mask because you're a complete and utter idiot.

SIMON LOMAND: You need to put one on, you selfish bastard.

LANGFITT: This is Simon Lomand, who runs a clothing company.

LOMAND: The mask thing is absolutely ridiculous. I mean, people - you know, surgeons, doctors have been wearing masks for years. There is no actual substance behind any of it.

LANGFITT: Lomand has friends who've latched onto conspiracy theories.

LOMAND: They go down the YouTube rabbit hole and believe everything that they read in these peculiar things that they subscribe to - i.e., the QAnon stuff. Once you've gone down that rabbit hole, it's very, very difficult to get back out again.

LANGFITT: In Trafalgar Square, in the shadow of Nelson's Column, protesters break into song.

UNIDENTIFIED PROTESTERS: (Singing) Singing, we are the 99% - come on - singing, we are the 99%...

LANGFITT: That's a gross exaggeration, but conspiracy theories appear to be gaining traction here. Oxford University researchers surveyed 2,500 people in England in May. One in 4 endorsed conspiracy theories about the pandemic to some degree; 1 in 10 genuinely believed them. Researchers wrote, such ideas do not appear confined to the fringes. Stephan Lewandowsky is a professor of cognitive science at the University of Bristol.

STEPHAN LEWANDOWSKY: What a pandemic does is to give pretty much all of us a sense of having lost control. For some people, a conspiracy theory is offering psychological comfort. It is easier to imagine that there are some evil people responsible for this pandemic rather than a random event involving some animal somewhere in China.

LANGFITT: COVID cases are back on the rise here, and the government is imposing more restrictions. Again, Stephan Lewandowsky.

LEWANDOWSKY: People who engage in conspiratorial thinking are less likely to comply with social distancing measures and mask wearing. The more people believe in conspiracies, the less likely they are to do the right thing, constituting a risk for themselves, but also society.

UNIDENTIFIED PROTESTER: Do you believe the science?

UNIDENTIFIED PROTESTERS: No.

LANGFITT: The protests in Trafalgar Square - there've been three since the end of August - attract people who believe in various conspiracy theories.

RUSSELL YARDLEY: They're lying to us on every level, and they're inflating figures to make us scared.

RISA LAURENT: Children being trafficked and babies in FedEx boxes...

JANET WALMSLEY: It's a one-world government thing that they want to rule the world.

LANGFITT: That was Russell Yardley, a retired London police officer; Risa Laurent, a laid-off care worker; and Janet Walmsley, a retiree in her 70s.

If there is a second lockdown here, will you abide by it?

WALMSLEY: No, I will not obey. I will travel. I will go to the shops. I will not wear a mask ever - never, never - over my dead body.

LANGFITT: The British government's often muddled response to COVID has confused many Britons, including Ginette Craig, who's come here just to try to figure out what's going on. Craig is waiting for a surgical procedure to remove fluid from her abdomen, which has been postponed because of the pandemic.

GINETTE CRAIG: I've had my operation canceled three times now. I'm finding it hard to breathe. I'm finding it hard to eat. People like myself just don't matter anymore.

LANGFITT: COVID confusion has created an opening for QAnon and other conspiracy theories. Aoife Gallagher is an analyst with London's Institute for Strategic Dialogue, a think tank which focuses on extremism and polarization.

AOIFE GALLAGHER: What we saw in the middle of March - literally coinciding with when lockdowns came in worldwide - was a drastic increase in QAnon conversation. I think it was like a 175% increase in QAnon discussions on Facebook alone in March.

LANGFITT: QAnon began in far-right forums on the Web but has spread far beyond that.

GALLAGHER: Now it seems to be pulling in people from the left of the spectrum, like very, very anti-establishment thinking and almost, like, very, very liberal people as well - people that might be very health conscious and might be a bit wary about vaccines. We're seeing people that are highly educated, people with Ph.D.s that are getting into these conspiracy theories.

LANGFITT: Unlike in the U.S., QAnon's influence here doesn't seem to have an overt connection to President Trump. One thing everyone shared at these protests, though, was a distrust of government and traditional media. Whenever the coronavirus subsides, professor Lewandowsky expects the related conspiracy theories to go into remission but not disappear because the factors that fueled their growth - distrust, misinformation and the power of social media - aren't unlikely to change anytime soon.