Peanut butter is sold as a health food, and the most potent natural liver carcinogen known to science was discovered because it killed over 100,000 English turkeys in 1960. That year, young turkeys on farms within about a hundred miles of London began to die. They went quiet, stopped eating, sat with their heads drawn back and were dead within days. Vets had never seen anything like it. They called it Turkey X disease. By the time it burned out, well over 100,000 birds were dead, along with ducklings and young pheasants on other farms. The common thread was the feed, and a new ingredient in it: peanut meal, shipped in from Brazil. Outbreak after outbreak traced back to mills that had used the same Brazilian groundnut meal. The meal had been colonised by a mould, Aspergillus flavus, which makes a poison the scientists named after it: aflatoxin. Fed to rats in the lab, it wrecked their livers and then gave them liver cancer. For years afterwards the standard test for a suspect batch was to feed it to day-old ducklings and look at their livers. It is now classed as a definite cause of cancer in humans, and it lives where the mould lives: in peanuts, maize, tree nuts, cottonseed and dried figs, crops stored warm and damp in bulk. It is behind tens of thousands of human liver cancers every year, mostly in countries where peanuts and maize are the daily staple. Europe sets a legal limit for aflatoxin in peanuts and turns shipments away at the border every year for breaking it. Nobody has ever needed a border inspection for aflatoxin in a sirloin. The turkeys were fed peanuts because peanuts were cheap. We are told to eat them because they are full of healthy fats. Both were sold the same nut.

Customer: "Why did mutton disappear? My gran talked about it like it was Sunday itself." Butcher: "Because you stopped wearing wool." Customer: "What's wool got to do with it?" Butcher: "Everything. For a thousand years this country kept sheep for the fleece. The wool paid the rent. A ewe was clipped every summer for six or seven years, and when she'd given her last fleece she gave you Sunday dinner. Every leg of mutton was a sheep that had already paid for herself." Customer: "And lamb?" Butcher: "A luxury. You'd no more eat a lamb than burn a five-pound note. That's seven fleeces walking into the oven." Customer: "So what changed?" Butcher: "The jumper went plastic. From about 1960 a fleece was worth less every year until it was worth nothing, and today a farmer gets roughly what it costs him to shear her. Nobody keeps a sheep seven years to collect two pound a time, so they bred her for the one thing left that paid." Customer: "Meat." Butcher: "Fast meat. Lambs that fatten by four months and leave before they've cost anything. Inside one generation the sheep went from a wool animal with a dinner at the end to a dinner in a hurry that grows a coat nobody wants." Customer: "And the old ewes?" Butcher: "Still coming off the hill every autumn, and still the best eating in this shop. Five years of grass and heather in the fat, meat the colour of beef, and she's never seen a bag of feed in her life. Grass-fed is the label people pay double for on a steak. On her it's just Tuesday." Customer: "Why's she half the price, then?" Butcher: "Because nobody asks. A leg feeds eight, low oven, four hours, and the gravy off it will make you forget lamb was ever invented. The old boys who come in for it never bother with anything else." Customer: "My gran used to say the fat was the point." Butcher: "Your gran was right about most things. The jumper went to plastic and the roast went with it, and nobody noticed they were the same sheep. You can undo the whole thing in one shop. I've got the leg. The jumper's your problem."