A provocative campaign has today launched on the London Underground, aiming to bring to light the secretive practice of slaughtering pigs in gas chambers.
Supported by comedians Diane Morgan, Jen Brister and Shabaz Ali, TV’s Dr Amir Khan, and TV personality and athlete Mathew Pritchard, the ads challenge the industry’s claims that CO2 gassing qualifies as “humane slaughter”. Each high-profile supporter dismisses the claim in their own words and lands with the same conclusion: “I don’t buy it.”
In England and Wales, 90% of pigs are slaughtered inside CO2 gas chambers, which according to a 2025 report by a government advisory body, causes severe pain, fear, anxiety, and respiratory distress. The government’s December 2025 animal welfare strategy announced a “phase out” of CO₂ gassing for pigs, but Project Slingshot, the group behind the campaign, believes the commitment is little more than hot air. They have accused the government of capitulating to an industry driven by profits, not welfare.
Other supporters of the campaign include comedian Simon Amstell, author and historian Rutger Bregman, MP Neil Duncan-Jordan, actor Sir Mark Rylance and Meat Free Monday’s very own Paul, Mary and Stella McCartney who said: “Project Slingshot is doing exactly what needs to be done: pulling back the curtain on factory farming so that people can make informed choices. That moment of awareness is what changes minds.”
Sir Mark Rylance said, “We’re killing nine out of ten pigs in gas chambers. The government knows it causes pain and fear. The industry knows we’d object if we knew. So they made sure we didn’t.”
While the practice of slaughtering pigs inside gas chambers is indeed little known, when people do find out, the majority opposes it. In a survey commissioned by Project Slingshot, 81% of Brits said they found the practice unacceptable.
“The powerful agribusinesses behind the UK pig industry know the secret formula: make a killing by spending less on killing,” said Project Slingshot’s co-founder Matthew Glover. “We know that ending the CO2 gassing of pigs is a David-and-Goliath fight. They have the power. They sit on government boards. But we have the truth, and if they don’t like what we are saying, our lawyers are ready.”
Project Slingshot’s goal is to ensure gas chambers – and all the other unacceptable practices and outcomes associated with industrial factory farming – are brought into the light, and ultimately to end factory farming by 2040.
More than 750 ads will appear in 206 London Underground stations, and there are 2,200 more inside tube carriages, for two months from today. The stations include Euston, Charing Cross, Liverpool Street, Embankment and Kings Cross St Pancras.