Rishi Sunak has been challenged to go vegan for a month in exchange for a £1m donation to charity.
The £1m comes from a wealthy donor via a vegan organisation that argues animal agriculture is a leading cause of damaging greenhouse gas emissions.
The donor and Generation Vegan say the UK cannot meet its net-zero target without drastically cutting consumption of meat and dairy, which account for “at least 16.5 per cent of man-made emissions”.
From Monday, all giant billboards at Westminster Tube station will publicise the challenge to Mr Sunak, with adverts on platforms, in trains, on escalators and on ticket gates.
And full-page adverts publishing an open letter to him will appear in national newspapers from Saturday and over the first 10 days of the new year.
In the letter sent to No 10 on Wednesday, Naomi Hallum, chief executive of Generation Vegan, writes: “We would like to donate £1m to a charity of your choice in exchange for you adopting a plant-based diet for one month.
“Adopting a plant-based diet is one of the best things we can do to champion British farmers and our countryside, while also meeting our emission reduction commitments and supporting public health.”
A No 10 spokesperson said it had no comment to offer and was unable to say whether the prime minister had been made aware of the potential donation.
Last year former US president Donald Trump refused a similar offer, claiming he was “afraid of losing his brain cells”, a book claimed.
The Pope did not respond to the same offer, but he gave the campaign his blessing and later urged young people to eat less meat.
The vegan activists told the prime minister that animal agriculture accounts for most of the UK’s farmland yet provides only a third of calories and less than half of all protein consumed.
“To feed the same number of people on a plant-based diet would require just one-sixth of the land, leaving 14.5 million hectares available for alternative uses, such as nature restoration and rewilding of habitats as part of carbon sequestration initiatives,” the letter says.
Plant-based diets support farmers already trying to switch to more animal-free farming, they add, and help the UK deliver on its commitment to meeting climate targets.
A peer-reviewed study last year calculated that animal agriculture is responsible for at least 16.5 per cent of man-made greenhouse gas emissions and they would reach 49 per cent of the 1.5C target by 2030 without action.
Exeter City Council plans to serve only plant-based food at internal events, and earlier this year Oxfordshire County Council announced it would serve only vegan food at its events.