Celebrity-Backed Billboard Campaign Warns London Commuters About Factory Farming

A celebrity-backed billboard campaign is warning London Underground commuters about the realities of factory farming and so-called “humane slaughter.”

New billboards have appeared in more than 200 train stations and 2,200 tube carriages across London, UK. Each one highlights how CO₂ gas chambers are currently considered a humane slaughter method for pigs farmed in the UK.

The Ban CO₂ Gas Chambers campaign is the first from Project Slingshot, a self-described “global crew of citizens, designers, investigators, filmmakers, and researchers who refuse to look away.” Many of the billboards feature one of Project Slingshot’s celebrity backers, along with a quote and the slogan “I don’t buy it.”

Public figures such as Dr Amir Khan, Sir Mark Rylance, Rutger Bregman, Peter Singer, Paul, Mary, and Stella McCartney, Jen Brister, Shabaz Ali, Mathew Pritchard, and Diane Morgan have all backed the campaign. “This isn’t just a few bad apples,” said Morgan. “It’s the whole f**king orchard. Don’t buy it. I certainly f**king don’t.”

‘What we are calling out is industrial-scale gaslighting’

“Today is the most important day of my working life so far,” Mathew Glover, the co-founder of Project Slingshot, wrote on LinkedIn yesterday morning. “We are taking aim at the meat industry’s most cynical piece of spin, the claim that gassing pigs in gas chambers qualifies as ‘humane slaughter’. Ninety per cent of pigs in England and Wales are killed this way, and most people don’t know.”

“The government’s own advisors first recommended ending the practice in 2003 for reasons that become obvious the moment you see the undercover footage the industry has spent so much energy trying to bury. Twenty-three years later it is still the industry standard,” Glover said.

He added, “What we are calling out is industrial-scale gaslighting.”

The UK’s proposed CO₂ gas chamber ban

Photo shows a new billboard from Project Slingshot's Ban CO2 Gas Chambers campaign, featuring a picture of a pig and warning commuters about the reality of factory farming and so-called "humane slaughter" methods, such as CO2 gas chambers — Project Slingshot “The meat industry calls gas chambers ‘humane slaughter.’ Don’t buy it.”

In November last year, a report by the independent Animal Welfare Committee (AWC) called for the CO₂ “stunning” of farmed pigs to be phased out in the UK.

In January, the government’s updated animal welfare strategy confirmed a phase-out. However, the proposed change has been met with some pushback.

The UK kills 10 million pigs for food every year. The national pig population is roughly 4.7 million at any one time, of whom more than half are factory farmed. CO₂ stunning is cheap, and uptake increased from 52 percent in 2013 to 90 percent in 2025.

According to the AWC’s recent report – and accounts from animal rights activists, charities, scientists, and investigators – there is “significant” evidence exposing pigs to CO₂ causes “avoidable” pain, respiratory distress, and fear before death.

Roughly 81 percent of the British public opposes CO₂ stunning. “I looked up ‘humane’ in the dictionary and, I have to say, gassing didn’t come up,” Morgan said.

Find out more about Project Slingshot and how to support the campaign here.