The Walkers Crisps Conspiracy That Has People Convinced We're in an Alternate Reality

"The wrong flavoured crisps can cause a ripple effect throughout the whole of world history."

That's Mark Garnett, senior political lecturer at the University of Lancaster, on a mystery that's been circulating for some time. A mystery I stumbled upon one night in the pub.

I was tucking into a bag of Walkers salt & vinegar crisps, ripped at the seam and spread invitingly over the table, when I lamented that Walkers had switched the colours of salt & vinegar and cheese & onion packets, from blue to green and green to blue, respectively. Common knowledge, I thought – but my friend was adamant they'd always been this way around. I whipped out my phone, only to be gaslighted by the FAQ section of the Walkers website:

I had no idea – sitting in that sweaty Fuller's, licking additive-laced vinegar off my fingertips – that I had just stumbled on what could be the biggest corporate stitch-up since the Enron scandal. It felt baffling to have my personal account of history denied. So I decided to investigate via the medium of making a podcast about it – and, to kick things off, tracked down Gary Lineker, long-time Walkers representative. He couldn't have been clearer: he remembers a switch.

"Oh, long, long, long ago," he recalled, visibly baffled. "I don't know. It's before I started, so it's over 25 years ago." I asked him why they made the switch. "I think it might have been when Pepsi bought them…" I pushed: "So about… '89-ish?" "Maybe," said Gary. "I don't know – I can't answer that question. Google it. I'm sure you can find it." When I told him Walkers deny it ever happened, he was unequivocal. "No they don't, everyone knows it happened."

Aside from the weirdness of the face of Walkers contravening the corporate line, Gary's suggestion to google it doesn't help much. The search engine doesn't offer any picture evidence of the original colours of crisp packets. Not one old photograph of some 80s kid in prescription aviators clutching a bag of Walkers green cheese & onion. No ancient blue salt & vinegar packet knocking about on eBay. Not a single retro Walkers ad on YouTube that betrays a colour-inverted past. But could this – hypothetically, at least – be due to search results being deliberately wiped? How certain can we be that Google isn't in the pocket of Big Crisp?

"I think that it is very easy for Google to do something like that when they basically control the content of the internet – and, I mean, they need advertising money and it's very, very easily possible, yes," says a software engineer at Google who asks to remain anonymous. He's a little sheepish when asked if Google has ever collaborated with brands to pull off such a clandestine act, but confesses that the tech giant "values close relationships with brands, and I think that maintaining good relationships with [Walkers owner] PepsiCo especially is well within our interest… I think that a lot of money changes hands."

A spokesperson for Google is quick to pour water on the implication. "Our search results are a reflection of what's on the internet, and we only remove results under very limited circumstances, such as when required by law," they tell me. "Webmasters have control over what is indexed by Google, so there is plenty of web content that Google does not see. And only a website owner can remove pages from the web."

Still as stuck as before, we're forced to grapple with the bulk of actual evidence: scraps of folk memory strewn around subreddits and the forums of Scottish football site pieandbovril.com. "I swear they were the other way round when I was a wean," says user BigFatTabbyDave, for instance, while Blootoon87 despairs: "I can't even trust my memories anymore."

There are also testimonials from around two-thirds of the people I've vox-popped, like a shopkeeper who has been selling Walkers for over 20 years from his off-licence in Brixton. "I definitely know that [the colours have] changed," he said. "The green pack always has been cheese & onion."

However, these recollections are all crushed underfoot by that condescending phrase "popular belief" in the Walkers FAQ.

This is not the first example of strangers claiming the same seemingly false memories. Many people remember the US kids' show The Berenstain Bears being spelt "Berenstein", for instance, or Sex in the City being called Sex and the City, or a movie about a genie called Shazaam that apparently isn't real. The phenomenon has a name, Mandela Effect, which comes from the masses of people who claim to remember Nelson Mandela dying in prison in South Africa in the 1980s, when he actually died in 2013.

Most leaders of Mandela Effect online communities plump for parallel universes, or Matrix-like glitches and simulations. "Many people who have experienced the Mandela Effect don’t know that we've shifted [universes] until we see an example, like your chips," says Lisa Bansley, who runs the Mandela Effect Project Facebook page and claims to have herself traversed dimensions.

A self-proclaimed member of the Illuminati I found on Craigslist has his own idea: "There is a possibility that the Illuminati is manipulating certain tiny aspects of people's lives in order to control them in a particular way." He told me about his Illuminati colleague's theory that if a company makes a small change in the world, and then denies it, this can gradually erode people's sense of reality.

"Perhaps it could be leading up to bigger and bigger events," he said. "If you look at, for example, a dictatorial regime, they start off usually very slowly, and very subtly become a dictatorship. They start to change very subtle things and they start to tell you that either these things are for your benefit or these things never happened, you're imagining it, and then the lies grow bigger and bigger."

Conspiracy theories aside, there's a specific Walkers advert that multiple people I speak to remember in startling detail, in which football teams swap blue and green shirts to mark the packets switching colours. "There was one which was switched," recalls Malcolm Green, the ad man who made the first Gary Lineker Walkers commercial, and other Walkers campaigns in the 90s. "I can't remember… yeah, I think the flavours were switched. Everybody knew that green was cheese & onion and blue was salt & vinegar, so I think we kind of switched the colours and it was all about that. But I just… God, I just can't remember, it's so long ago."

The advert also rings a bell for Larry Viner, who heads up the Advertising Archives. "Alarm bells," he says, "because I regularly get emails from people asking me very specifically about this thing, and I've never been able to track down an advert that confirms the urban myth that is still circulating, which doesn't mean that it didn't happen or that it doesn't exist, but I haven't been able to track it down."

When contacted for some kind of explanation, a PepsiCo spokesperson repeated the familiar refrain: "Contrary to popular belief, Walkers Cheese and Onion have always been in blue packets, and Salt and Vinegar have always been in green packets."

A 2014 YouGov survey found that 48 percent of UK respondents thought salt and vinegar packets should be blue, and 32 percent green. For cheese and onion, the results were 44 percent for green, 30 percent for blue and 10 percent for yellow. An accompanying article also noted that the colour of almost every large crisp manufacturer's packets, besides Walkers', is in line with public preferences – which could go some way to explaining the near-universal belief in the switch.

Either way, we're still left with some difficult questions. If the switch happened, why would Walkers cover it up? And, most importantly, who should you believe? The established narrative, or the alternative one? Who should you trust? Big brands? Google search results? Dimension travellers? Illuminati members? Gary Lineker? The British public? Their memories? Or your own?

The Walkers Switch is available on Spotify, Apple Podcasts or wherever you get your podcasts