You know what's really, really stupid about this whole shitstorm? The UK industry standard for acceptable levels of Listeria in food such as burgers is 100 cells per gram. Ergo, one quarter-pound burger could contain over 11,000 Listeria cells, and no-one at the Food Standards Agency would bat an eyelid at it being sold.
It only takes 1,000 Listeria cells to pose a threat to someone's health, and it has a 20% mortality rate.
But God forbid any meat that isn't beef getting into the beef burgers. THAT's what everyone chooses to flip a shit over.
This is a perfect example of why it's better to not know what exactly is in your food. I swear, if literally everything in it was printed on the labels, people would starve themselves to death.