In the summer of 1922 two men called George took part in the first attempted ascent of Mount Everest. George Mallory was an establishment man. A Cambridge graduate and son of a Church of England rector, he dressed in the respectable climbing gear of the time, a jacket and tough, cotton plus-fours. George Finch, his fellow explorer, was an outsider, a moustachioed Australian with chiselled good looks and an independent streak who liked experimenting with new contraptions: he took bottled oxygen to use at high altitude, and wore a specially commissioned coat made from bright green hot-air balloon fabric stuffed with the down of eider ducks.

Though climbers were already using sleeping bags filled with down, Finch’s fellow climbers initially mocked his bulky coat. That changed as they approached Everest. “Today has been bitterly cold with a gale of a wind to liven things up,” Finch wrote in his diary. “Everybody now envies my eiderdown coat and it is no longer laughed at.”

The two Georges turned back after their third failed attempt on the summit. Two years later Mallory joined another expedition to Everest, but went missing close to the top; his climbing feats were then romanticised by a hero-hungry public. Finch never tried again and pursued a considerably less romantic career as a chemistry professor. Yet ultimately he had a greater impact than that of the better-known George. Today, climbers at high altitude routinely carry oxygen. His other innovation has been even more influential, extending far beyond mountaineering circles: on the 1922 expedition George Finch invented the puffer jacket.

The new coat quickly caught on. When Edmund Hillary and Tenzing Norgay finally made it to the top of Everest in 1953, they wore down snowsuits. No mountaineer today would do without one (as one climber put it a few years ago, “the main problem with climbing Everest nowadays is pissing through a six-inch suit with a three-inch penis”).

As well as scaling the highest peak, the down coat has travelled far more widely. The first commercial down-filled jacket was patented in 1940 by Eddie Bauer, intended for outdoor enthusiasts. Today, a coat invented for mountain explorers is more often used to protect the metropolitan masses from the elements. From Tokyo to Toronto we face the winter dressed in down, even if our main activity is to scurry a few city blocks. Duvet-coats are now sold by high street and designer brands alike. And fortunes have been made off the back of them: Canada Goose, which specialises in “extreme weather” wear, has built a multi-billion-dollar brand from its puffer coats; so has Moncler.

Feather stuffing, once the height of luxury, has become ubiquitous. Over the past quarter-century, our global demand for warmth – even on a short shopping trip – has led to a tripling of the global trade in feathers by volume. Never mind being light as a feather, the raw plumage that drifts across borders each year is equal to the weight of nearly 90,000 cars. And 80% of those feathers come from one country: China.

The trade in feathers is not a simple case of supply meeting demand. The down in our coats is, in fact, a by-product of the ducks and geese that end up on dinner tables. In terms of price per weight, down feathers – the soft, fuzzy ones on the bird’s breast – are the most valuable part of a duck, worth $25-50 per kg, roughly ten times as much as the meat. But a typical bird yields some 2.5kg of meat compared with just 15 grams of down, so a duck’s value lies mostly in its flesh. The soft feathers account for just 3% of its value, so abattoirs see those fluffy hairs not as a treasured commodity but detritus.

Most of those abattoirs are in just one country: thank the vast and still rising Chinese appetite for duck and goose for your warm coat. These birds – roasted, steamed or salted – have long been part of China’s cuisine. In the north, restaurants carve up crispy Peking duck. In the south, people like the succulent roasted version. In Nanjing in the east, duck banquets use every inch from beak to wing. During the economic boom of recent decades meat, which was once a rare delicacy, has become a regular indulgence. Fast-food stalls selling braised duck necks are a staple of Chinese railway stations. China has two multi-billion-dollar firms that specialise in shrink-wrapped, ready-to-eat duck snacks.

In 1978, when China began to rebuild its economy after Mao’s disastrous rule, the average citizen ate just 270g of duck a year. Today, they consume eight times that amount, over 2kg. The Chinese account for most of the global demand too: two out of every three ducks eaten worldwide are in China. On the goose side of the ledger, China accounts for a startling 95% of the world’s geese slaughtered each year. The more waterfowl the Chinese eat, the more feathers there are. If the insatiable appetite for duck in China today is a metaphor for the country’s rise over the past 30 years, then the down feathers in your coat are the surprising flourish.

A Cherry Valley duck is a handsome creature. She carries herself elegantly, with a long neck, puffed-out chest and a broad, aquiline bill. The name of her breed conjures up the image of a rural idyll. But her life, in a small corner of eastern China, is nasty and short.

She spends her 40-odd days on Earth in a makeshift barn, its walls slapped together with heavy plastic sheeting. She is packed into a small room with thousands of other ducks, walking on wooden slats through which her excrement falls. Inside the barn there is a cacophony of squeaks. The youngest emit high-pitched chirps. As the ducks age their coats turn white and their calls deepen into honks.

In her six weeks inside the barn, about 150km inland from Shanghai, the Cherry Valley duck never once feels the sun on her back. But she cannot escape the light. Bare, fluorescent bulbs hang from the ceiling and are never turned off, so that she is stimulated to eat as often as possible. She reaches maturity roughly twice as fast as she would in the wild.

Raising ducks is easy once you get the hang of it, says He Xianzhong, who owns the farm. He used to work long hours in a steel mill. Now he visits his ducks just twice a day, to feed them. The money isn’t great but he has had plenty of time to help his son with his schoolwork. That paid off. The son is now an engineer at a semiconductor firm in Shanghai.

Around her 40th day, the Cherry Valley duck is pushed down a chute at the back of the barn. Squawking madly, she is loaded into a crate and driven 15 minutes down the road to her final destination, the Jiahui abattoir. For a few seconds, she may even catch a glimpse of sky. She squawks ever more frantically as she is turned upside down and her feet are slotted into metal clamps on an aerial conveyor belt. She is whisked through electrified water, the quick zap leaving her unconscious. A worker jabs a knife into her gullet and blood pours out. The belt then passes her lifeless body through an industrial washer, before dropping it into an enormous machine a bit like a giant vacuum cleaner, which sucks off her feathers. After the ducks have been stripped, workers in pale-blue smocks scoop up clumps of feathers sodden with water and streaked with blood, and haul them away by wheelbarrow. At the far end of the complex, the dirty, prickly plumage is washed, dried and bundled into large green bags, still emitting a barnyard odour.

That, at least, is the best version of events. The feather industry has ridden the wave of the current desire for “natural” and sustainable products, in contrast to many clothing fibres that contain plastics. But the life cycle of a present-day duck is hardly natural. And posthumous harvesting is not the only way to glean soft down from birds. Over the years animal-rights campaigners have made a succession of allegations that some down used by clothing companies has been torn from the bodies of living birds, or “live-plucked”.

In 2016 People for the Ethical Treatment of Animals, an American campaign group, released a video showing workers in dingy rooms in China ripping out feathers from honking geese, leaving them bloodied and frightened. A similar Swedish documentary in 2009 led IKEA to phase out a line of bedding that may have contained live-plucked feathers. Most such charges relate to goose feathers, which are larger and more often go into bedding, rather than duck down.

Chinese producers are adamant that such allegations are overblown. The national down association says live-plucking is financially feasible only for top-end bedding, which makes up less than 1% of China’s down production. Tearing out handfuls of down feathers, bird by bird, is a costly, labour-intensive process. China has no shortage of feathers that have been efficiently plucked from freshly slaughtered fowl by industrial sorting machines post-slaughter. And farmers say that the trauma of live-plucking damages the bird’s meat, and therefore its value.

The down industry has been trying to root out the practice, however marginal. Since 2014 international clothing firms have established animal-welfare standards and employed independent auditors to inspect factories and farms. But though a clothing company may have just one or two down suppliers, many suppliers have contracts with five or six abattoirs which, in turn, get birds from dozens of barns. Tot it up, and a single coat or duvet can easily contain feathers from over a hundred farms. Auditing that supply chain is both difficult and pricey. Your duvet coat may not be quite as cosy as it seems.

In your hand a down feather looks like the raggedy head of a dandelion. But peer into a microscope and its fine filaments resemble a forest of perfectly symmetrical trees. These filaments, known as barbs, are about 20 micrometres in width, or “thinner than a coat of paint”, says Matthew Fuller, a British chemist and avid climber. He has spent more time looking at down than just about anyone else: he completed the world’s first P h D in down and its uses.

The fluffy feathers under Fuller’s microscope bear little resemblance to the grubby ones in the abattoir. But all feathers are a marvel. Scientists have tried in vain for years to create a synthetic material that is as insulating and breathable as down. Why can we put a rover on Mars but not create a material superior to down?

Down has time on its side: some 150m years ago, raven-sized dinosaurs with feathery coats roamed the Earth. Feathers have been tested and perfected by evolution. “Nature thought long and hard about this,” says Fuller. Yet there is nothing special about the material that comprises down. It is mainly keratin, the same ingredient as in fingernails, hair and animal horns. The secret to its warmth is its structure. The barbs overlap to form a delicate lattice that traps heat. And they are a tough, lightweight composite, composed of hard tubes that provide strength and a soft matrix that absorbs impact. Jutting out of each barb are barbules, even smaller filaments. They are just rigid enough to avoid getting tangled, and just long enough to prevent heat from transferring across the resulting air pockets. Individually, a down barb is blown about in the gentlest breeze. Clustered together, they are mighty.

The importance of down to birds is revealed by simple maths, says Thor Hanson, author of “Feathers: The Evolution of a Natural Miracle”. Of the 2,000 to 4,000 feathers that cover an average bird, most are downy: they have fewer than 100 feathers for flight. Down allows penguins to lay eggs in Antarctica, finches to thrive in a Canadian winter and cranes to soar to altitudes where the air is -50°C. Down is nearly as light as air, an obvious virtue for a bird. Fur, by contrast, is far heavier.

Synthetic fibres with names such as Thinsulate and Climashield seem to promise top performance, yet they remain pale imitations of down. A mountaineer would have to wear 11 pairs of polypropylene long johns to achieve the heat retention of one down-filled expedition jacket, says Hanson. For now, nothing beats a good duck.

As you walk into the feather factory, downy particles dance in the air like snow flurries. Bags of raw, pre-treated feathers lie in wait at the entrance, reeking of their barnyard past. The feather-sorting facility consists of tall, green metal silos, some 20 metres high, into which workers dump bundles of feathers and pump in air. Down floats to the top; heavier feathers settle at the bottom. Repeated several times, the down is separated into different grades. The rear of the factory, at the end of the treatment process, smells like freshly laundered linen.

The down from roughly one in every 30 ducks eaten in China ends up in the hands of Michael Mao, an earnest middle-aged man with wire-rimmed glasses. He handles the feathers of 300,000 ducks a day. Mao’s surname, appropriately, can mean feather: his English nickname is Mr Feather.

Mr Feather’s company is one of the biggest in Xiaoshan, a suburb of Hangzhou, near Shanghai, which is known as China’s “down town”. Xiaoshan has played a pivotal role in China’s emergence as a down superpower. Many such specialist towns grew up in China over the past three decades as the country became the world’s biggest exporter of manu-factured goods. In nearly every industry the formula was similar: after a few entrepreneurs blazed the trail, entire towns devoted themselves to a particular activity, drawing on a vast pool of rural migrants. One town was known for making zips, another for lighters, yet another for vibrators.

Xiaoshan is located in the coastal province of Zhejiang, at the intersection of several key industries. Farmers in the surrounding countryside raise ducks. In the 1980s some local residents opened clothing factories, creating demand for down. Others started producing electric fans, which were a critical tool in the industrial production of down: workers could dry feathers mechanically rather than laying them out in the sun, as they used to. And so it began. Feathers were collected from farms and shipped to Xiaoshan, where they were cleaned and sorted, separating soft downy balls from prickly quills, to leave the finest, fluffiest plumage. Hundreds of down producers set up there.

Just as China’s appetite for eating duck expanded the supply of feathers, so Xiaoshan’s intense focus on down production reduced the price of the finished product. Taken together, these two trends transformed the down industry. People had used plumes in their bedding for centuries, and in their coats for decades. But such products were pricey luxuries usually made by a small pool of producers in Europe. It took China’s economic boom to bring feathers to the mass market.

Mr Feather’s company, Samsung Down, was one of these (it is not related to the South Korean electronics giant of the same name). Mr Feather started as a salesman at a smaller firm in 1998, when he was 20. A recruiter visited his vocational school looking for students who met two conditions: they had to have good grades and come from a poor family – the down company wanted clever employees who would work hard. Mr Feather was the son of farmers who paid for his schooling by cleaning classrooms. He soon got his break, selling 70,000 sleeping bags to a Canadian buyer, a big deal for the time. The buyer stayed at the factory for six months while the bags were made, so Mr Feather took advantage of another opportunity: he learned English, establishing himself as the point person to deal with foreigners. Needing someone with such skills, Samsung Down plucked him to work for the firm.

He worked his way up to become a director at Samsung Down and a passionate ambassador for feathers. The firm’s English slogan, “We love down, we do”, makes up in directness what it lacks in poetry. The factory showroom is a United Nations of waterfowl plumage: glass display boxes contain feathers from Romanian goose, Siberian goose, Polish duck, Peking duck and, rarest of all, Icelandic eider duck. Mr Feather asks me to close my eyes and hold out my hands. The small ball of Icelandic eiderdown he places in one is so light that I feel nothing in either hand until, after a few seconds, one palm begins to warm up. The eider is unique in that it isn’t killed for its meat but it moults pure down, which farmers harvest from abandoned nests. Duvets made entirely from eiderdown can cost $10,000.

Samsung Down’s clients are content with less exotic fare. Some buyers want only the raw output: cleaned, sorted down. Others, including Marks & Spencer and Macy’s, buy finished products. At the company’s textile factory nearby, hundreds of workers sit at sewing machines with stacks of white fabric piled beside. In a seemingly endless whirl of motion, they shape formless material into duvets and pillows. On another floor, workers stuff feathers inside cut fabric, before sealing it shut. Products are then loaded into boxes and stacked by forklifts, ready to be shipped around the world.

Before that, a small sample makes one more stop, to a nondescript high-rise: the China office of the International Down and Feather Testing Laboratory. One peculiarity of the puffer’s popularity is that its defining feature – the feathers – are invisible in the final product. Unscrupulous producers may try to pad profits by crushing hard feathers to make them resemble down, swapping in cheap chicken feathers, glueing bits of down together to look like the prized, sticky variety, or merely skimping on the amount of stuffing they use.

At the testing lab, coats from Gap and Columbia sit alongside IKEA pillows, awaiting their turn. Staff cut open finished products to weigh how much down is actually in them. In another room technicians clad in white lab coats, blue hairnets and masks examine feathers for contaminants and test their water resistance. In a third office a technician uses giant chopsticks to stir a clump of goose down in a two-foot-tall glass cylinder, and then drops a special plate over the plumage to make the most crucial measurement of all: the down’s “fill-power”, or fluffiness, which tells you how warm your coat will keep you. Tests complete, the feathers are nearly ready to take their final flight.

In the waning days of 2018, Canada Goose, one of the most well-known brands devoted to down, was due to open its inaugural store in China. The omens were bad. China had started a nasty diplomatic brawl after Canadian officials detained a Chinese corporate titan on a judicial extradition request from America. China’s state media vowed that Canada would face “serious consequences”. Nationalists called for a boycott of Canadian goods, homing in on the popular down-filled parkas as a target. Canada Goose delayed the opening of its Beijing store. On December 28th it finally opened its doors. Sure enough, the store was swamped – not with protesters, but with Chinese consumers coming to buy its coats. Many had waited outside in freezing temperatures for up to an hour. Canada Goose is just one example of the fortunes that can be made from feathers. Its revenues nearly quadrupled from 2016 to 2019. But plenty of others – Moncler, North Face, Patagonia, to name a few – have also struck it rich with down attire. And, as the tempest of shoppers at the Canada Goose opening in Beijing showed, in China’s biggest, wealthiest cities, ducks in China are now often as popular for their down as for their meat. China is riding a fashion trend that has lasted well over a decade. When clothing companies shifted production to China in the 1990s and early 2000s, many took advantage of the easy availability of feathers to start offering down-filled coats as part of their winter lines, crafting sleeker and more stylish items with better shell material and stitching that no longer left feathers butting through fabric. The roly-poly look has become so popular that many high-street brands sell lookalike coats stuffed with less cosy polyester. But the pricier and warmer feather-filled ones command the greatest allegiance. For Chinese producers the triumph of down is bittersweet. On the one hand they are indispensable to its success. Over the past year, as the us -China trade war heated up, President Donald Trump slapped tariffs on feathers and down along with thousands of other items imported from China. Rather than welcome this, American clothing firms pleaded for leniency for their Chinese partners. David Sweet, chair of the American Down and Feather Council, a trade body, told a government hearing that the only way to lessen dependence on feather imports would be for every American to eat two ducks a year –20 times as much as they currently do. Time and again the fill-power of Chinese ducks and geese has proved equal to that of their European counterparts. Yet though almost every puffy coat on the market contains Chinese feathers, few advertise this. Take Canada Goose’s iconic parkas. The company proudly touts them as Canadian made. Their filling, it has previously stated, comes from one source: Feather Industries Canada, a down-procurement company. The website of Feather Industries Canada, in turn, has a large section devoted to Canadian down, “the product that we are most proud of”. Yet it also says that it gets its down from ”suppliers all over the world”. In a separate note it acknowledges that, in general, most down “comes from the Orient”. It refrains from mentioning China by name. This does not mean Canada Goose is less good than it claims. Feather Industries Canada gives strict quality assurances. It pledges to buy feathers only from farms that its employees have visited and that treat birds humanely. But much of its marketing obscures an essential fact: that its clothing relies on plumage of Chinese provenance. Perhaps it is time for a second Chinese revolution to shake the feather world. It took China’s appetite for duck meat to make down so plentiful. Now that its people have acquired a hearty appetite for down coats, its companies are scrapping for a bigger share of the clothing market – rather than simply filling the coats and coffers of others. George Finch proved a century ago on the slopes of Everest that the appeal of a coat has as much to do with the soft down inside it as its style. Who knows? Someday a brave soul may launch a luxury line that proudly proclaims the true nature of its stuffing. China Duck has a certain ring to it.■ Additional reporting by Qin Qian in Shanghai