This is her latest idea, albeit preposterous, to save our dying planet.
She said that 80 per cent of global warming comes from livestock therefore people should go vegan instead of destroying the planet.
"There are 25 alternative types of milk. Why do we not try drinking rats' milk, cats' milk or dogs' milk?" The Sun quoted Mill, as saying.
"I'm not telling people to go vegan overnight. But if they stop drinking their cows' milk lattes maybe this sort of thing won't have to happen," she added.
However, experts were not impressed with Mills' idea.
"It sounds ludicrous to me. How on Earth would you get the milk out?" Prof Ben Mepham, an authority on milk production, said.
The 39-year-old former model addressed the public at Speakers' Corner in Hyde Park, Central London.
However, not even one person among the public turned up to see her launch a campaign by vegetarian group Viva!