'Transmit the viands!' called the young Emperor Pu Yi, imperiously. Dinner time was whenever he felt like eating, there were no fixed hours. 'Transmit the viands!' called the junior eunuchs to the other eunuchs standing in the main hall. The order passed like a Chinese whisper from eunuch to eunuch, until it finally reached the yu shan fang, the Imperial Viands Rooms, as the kitchens were called. The cooks leapt into action. Before long, the eunuchs, in procession, were scurrying towards the emperor's quarters with dozens of red lacquered food boxes painted with golden dragons, and the tables on which to serve them. There were no dining rooms in the palace, so they set the tables up wherever the emperor happened to be, six or seven of them: two for main dishes, another in winter for the various soups and stews that sat over flickering flames, one for cakes, one for rice, one for congees, and another for salted vegetables.

Chinese emperors dined off yellow porcelain decorated with dragons, the imperial motif. There were strips of silver on the dishes, and silver chopsticks, because the metal was known to discolour in the presence of poison. (This was just a final precaution, because each dish had already been tasted by one of the eunuchs, who was watched carefully for signs of sickness before the emperor was fed.) The last emperor, Pu Yi, was presented with a mere thirty dishes at a sitting; the Empress Dowager Longyu, dining in her own quarters, with a hundred. The emperor ate alone, scrutinised by the eunuch servants. Whatever he had really eaten, their report to the senior concubines would be the same, dictated by ritual: 'The Lord of Ten Thousand Years consumed one bowl of old-rice viands (or white-rice viands), one steamed breadroll (or a griddle cake), and a bowl of congee. He consumed it with relish.'

Although I had been travelling in China for many years, I had never spent much time in the great northern capital, Beijing. I passed through every couple of years on my way to somewhere else, meeting up with journalist friends and eating the odd Peking duck, but I can't say I really knew the city. So, eager to move beyond Hunan and to broaden my culinary horizons, I spent a few weeks there after Christmas one year, researching Chinese imperial cooking.

These days the Forbidden City is just a museum. Pu Yi abdicated in 1912, at the tender age of five, when Republican forces had overthrown the Chinese imperial system after more than two thuousand years. Yet, under a bizarre agreement with the new government, he remained in the palace with the wife and senior concubines of his predecessor, and a vast staff of eunuchs, for a further thirteen years, until he was evicted by the warlord Feng Yuxiang's National Army in 1924. During that time, his life continued in all its pomp and ceremony, but his power ended abruptly at the dark-red perimeter walls. After the communist takeover of China in 1949, the palace was maintained as a museum and some of its workers lived within its confines, but later they too were shunted out, because of the risk of fire. Now, when the gates close at night, the citadel known as the Great Within (da nei) is deserted.

Central Beijing in January is magnificent, with its wide boulevards, stately architecture, and imperial yellow tiles glistening in the pale midwinter sun. At its heart lies the Forbidden City, which is being repainted and refurbished after years of neglect. Parts of it have been restored to gleaming splendour, but in the rest the paint is peeling, and the courtyards are worn and tufted with weeds. I sat, one bright morning, on the steps leading down towards the Inner Court, with the Last Emperor's autobiography in my hands, trying to imagine the smoke rising from the chimneys of the Imperial kitchens; the processions of eunuchs, their feet padding along the drafty colonnades; and the young emperor Pu Yi, surrounded always by his suffocating retinue of staff.

In theory, Pu Yi might have been blessed with the finest of diets. Imperial Beijing, after all, as the more-or-less continuous Chinese capital for 600 years, should have been one of the best places in the world to eat. The sumptuous cuisine of north-eastern Shandong Province, once the home region of Confucius, formed the bedrock of palace cooking. It was grandiose in style, with its fine stocks, rich soups and liberal use of fiendishly expensive ingredients. But it was always augmented by the tastes and techniques of other regions. When, during the Ming Dynasty, the Yongle Emperor moved his capital north to Beijing in 1403, the flood of officials who accompanied him brought with them chefs well versed in the kitchen lore of Nanjing, the old southern capital. During the Qing Dynasty, the Qianlong Emperor enjoyed lengthy sojourns in the southern Yangtze region, where he was seduced by the region's luxurious ways and fine gastronomy. He brought back with him chefs from centres of fine-dining like Yangzhou, who wove their own recipes into the imperial menus.

Into Beijing's melting pot of regional and ethnic foodways poured the finest produce from every corner of the empire. Tealeaves came in tribute from the hills of Zhejiang and Yunnan in the appropriate seasons; candied ginger from Yangzhou; Sichuan pepper from Qingxi in western Sichuan; and exotic delicacies like dried mushrooms and seafood ('treasures from the mountains and the seas') from far and wide.

The Qing emperors were Manchus from the northeast, not Han Chinese. Their ancestors had been nomads, eaters of bread and mutton, nibblers of pastries and candied fruits that were easy to transport on horseback across the northern grasslands. They drank milky tea, like the Tibetans and Mongols. After their conquest of China in 1644, the Qing ruling class never entirely lost their taste for such barbarian fare, and ensured that roast meats and certain sweet pastries became part of the repertoire of palace cooks. They also introduced Manchu dining customs, combining them with the more delicate eating habits of the Han Chinese: they carried knives in sheaths that had a pocket for chopsticks, so they could slice off chunks of meat and then eat them in the Chinese fashion. The blending of Han and Manchu culinary cultures at court reached its peak in the 'Man-Han' imperial banquet, a legendary three-day extravaganza of feasting that is said to have included more than 200 different dishes and snacks.

The emperor himself normally took two main meals a day: breakfast early in the morning, and the so-called 'evening viands' at around one o'clock. And then at six in the evening or thereabouts, he had an 'evening snack'. Every menu had to be formally approved by the Imperial Household Department before it could be cooked, and each was filed afterwards in the palace archives. (One, dating back to the reign of the Jiaqing Emperor records, for a day in 1799, a light breakfast served to the emperor's father at the start of the Lunar Year. It lists more than forty dishes, including soups made from bird's nest, duck, chicken, deer's tail and pork, vegetables, little steamed buns, New Year's cake, and 'all kinds of pastries and snacks'.) While the main Imperial kitchens supplied the emperor's grand daily provisions, smaller tea-kitchens provided informal refreshments, and pastry kitchens were at hand for buns and cakes.

Outside the palace, civil servants from all over China, working on rotation in Beijing and elsewhere, kept grand official residences. Highly educated, and often with discerning palates, they developed their tastes as they travelled, and goaded their private chefs to innovate at the stove. And so evolved a number of individual culinary styles that blended the flavours and cooking arts of different regions: some of them became so well known that they have survived until the present day, like the Tan Family Cuisine (tan jia cai) served in a restaurant of that name in the Beijing Hotel.

Sometimes the grand eating habits of the palace spilled out into the life of the common people. It was ex-palace chefs of Shandong origin, for example, who joined a man named Yang Quanren in setting up a roast-duck venture in Beijing in 1864. Roast duck had been around for centuries, but the traditional way of making it was in a covered oven (men lu) with a fire beneath it. Yang introduced the people of the capital to the roasting techniques of the palace kitchens, in which the birds were suspended over a fruitwood fire that gave their skin the most delectable crispness. His restaurant, Quanjude, became a national institution, and gave the world Peking Duck as we know it today.

If the emperor's daily meals were lavish, state banquets were arranged on an improbable scale: at the inaugural feast of the Jiaqing Emperor, for example, the kitchens laid on 1550 hotpots. When the British government first attempted to make contact with the Chinese court in 1793, the Qianlong Emperor entertained the British envoy Lord Macartney and his party to a 'sumptuous banquet'. Small tables, one for every two guests, were stacked with a 'pyramid of dishes or bowls piled upon each other, containing viands and fruits in vast variety'. The serving and removing of the dinner was conducted with such silence and solemnity that the Englishmen likened it to 'the celebration of a religious mystery'.

That January in Beijing, I set myself a mission to find the old kitchens of the Forbidden City. Several times I went there, buying my ticket at a booth in the outer courtyard, walking through one of the inner gates, a mousehole at the foot of towering red walls. I spent my first few visits exploring the grand halls, losing myself in the limitless lanes and the vast, abandoned courtyards.

The imperial kitchens were marked on my map as lying just to the east of the Outer Court, but when I eventually found them -- two long buildings with tiled rooves -- they lay in forbidden parts of the Forbidden City, closed to visitors. After a while, my curiosity overcame me, and I ignored the signs and slipped through a gate. The guards either didn't see me or turned a blind eye. In the end, however, the kitchens were still unreachable in their locked, walled compound. I stole through an open door into a neighbouring building that was filled with steam and fantastical pipes, the nerve centre of an old-fashioned central-heating system, but there was no way through. Walking deeper into the private office areas of the Palace Museum, I fell into conversation with a member of staff, and before long found myself drinking tea with a friendly and knowledgeable expert on the Forbidden City named Professor Luo. His office, at the side of a traditional courtyard, was stacked messily with books and periodicals.

Pu Yi ascended the throne on 2 December 1908, when he was not quite three years old. The formidable Empress Dowager Cixi, who had ruled at court since 1898, had suddenly decided to make him heir to the throne as she lay on her deathbed in November. So the young boy was wrenched, howling, from his family and installed in lonely splendour in the Forbidden City.

We talked for a while about imperial dining habits, and then, in an act of spontaneous kindness, he took me on a tour of the imperial collections in the museum. We saw the ritual bronzes of the Shang and Zhou dynasties, patterned with stylised beasts and birds; the heavy jars that were once filled with grain and sealed into tombs; the delicate white ceramics of the Sui. We walked through galleries that explained the ritual of imperial wedding feasts. Most intriguingly, Professor Luo told me that some of the palace storerooms had never been cleared, and were still filled with dried foodstuffs and medicinal herbs from the early twentieth century, when the Last Emperor still lived within its walls.

In his autobiography, Pu Yi condemned the excesses of the old imperial court, and said the Republican government had allowed him and his household to continue 'our prodigious waste of the sweat and blood of the people in order to maintain our former pomp and continue our parasitic way of life'. But he wrote his autobiography under communist supervision, and the communists clearly wanted to play up the wasteful extravagance of the Qing and the Republicans who succeeded them.

It was just the start of a strange and turbulent life. Pu Yi ruled, with his father as regent, for barely three years before his abdication in 1912. When, at the age of eighteen, he was rudely expelled from the palace, having continued to live there until then under the terms of his abdication agreement, he took refuge in the Japanese concession in Tianjin. In 1934 he became the puppet emperor of the Japanese vassal state of Manchukuo in northern Manchuria -- an ill-fated collaboration that led to his being branded a war criminal at the end of the Second World War. Following the armistice, he spent five years in a Siberian prison, and then travelled back to China by train in 1950, where he was imprisoned for another decade in an attempt to 'reform' him through labour and ideological indoctrination. In 1959, Pu Yi was formally pardoned by the communist state, and spent the rest of his life as an ordinary citizen in Beijing, working as a gardener and, later, a researcher in the imperial archives.

After my tour of the palace museum with Professor Luo, fantasising about deer's tail soup for breakfast, I became more and more hungry. But I couldn't find anything to eat. The chimneys rising from the old tea kitchens were cold, the imperial kitchens boarded up and empty, and there weren't even any modern snack bars for the tourists. In the end, my energy fading, I came across a few tables and chairs set up outside the hatch of some kind of stall. I laid down my heavy bag. Through a gate in the dark-red walls, I could see the end of the old imperial kitchens. But the only hot food being sold on that freezing January afternoon was pot noodles, cooked in water poured from a thermos flask. So I sat down with my lists of imperial delicacies, and my books about the lives of the emperors, and ate instant noodles with beef-flavoured sauce out of a disposable plastic bowl.

But was it even necessary to exaggerate? Pu Yi quotes the imperial records of food expenditure for a single month of his reign, when he was a mere four years old. Apparently, the tiny emperor, the empress dowager and four high consorts together consumed about two tonnes of meat and 388 chickens and ducks in that month alone, of which about 400 kilogrammes of pork and 240 chickens and ducks were destined for the emperor himself. That's about 14 kilogrammes of meat and nine birds every day, for a tiny child! Even in my wildest and most excessive periods of 'research' in China, I haven't come close to this. Needless to say, most of this extraordinary food budget must have been wasted, or siphoned off by the eunuchs, who were notorious for their embezzlement of imperial funds.

Food has always been of exceptional importance in Chinese culture. It is not only the currency of medicine, but of religion and sacrifice, love and kinship, business relationships, bribery and even, on occasion, espionage (legend has it that the Chinese organised a rebellion against their Mongol conquerors in the fourteenth century by hiding messages in mooncakes). 'To the people, food is Heaven,' goes the old and oft-repeated saying.

Once, when I was visiting the National Palace Museum in Taipei, I came across a rather peculiar exhibit. There, in a glazed display cabinet, on a delicate plinth tooled with cloud patterns in pure gold, sat what appeared to be a chunk of tender cooked pork. The skin was a rich, glossy brown, flecked with the dots of hair follicles. The flesh, layered unevenly with fat, drooped succulently over one edge of the plinth. It looked delicious, like a piece of belly pork that had been braised for hours in a clay pot with soy sauce, rice wine and sugar. My mouth watered… but the label on the cabinet was a stony reminder that the 'meat' was made from a piece of cold, hard agate.

This pork chunk is one of the most prized imperial treasures, spirited away from the Forbidden City when China was consumed by war. The Nationalist authorities loaded their pick of the precious objects in the palace onto a convoy of lorries, and drove them deep into the Chinese hinterland. As battle raged around them, and Japanese bombs fell, the custodians of the museum skirted the areas where the fighting was worst, and ultimately shipped their cargo over the straits to Taiwan, where the Nationalists were setting up their exile government. Incredibly, not a single object was damaged or broken in the course of this long and tempestuous journey.

A piece of pork fashioned out of precious stone, displayed on a golden plinth. I tried to imagine a golden joint of roast beef, studded with diamonds, rubies, emeralds and pearls, sitting amid the coronets and sceptres of the Crown Jewels in the Tower of London. But it was absurd, unimaginable. Only in China would you find a piece of common meat fashioned out of a precious material by master craftsmen and displayed among the treasures of the nation. It seemed like a metaphor for the seriousness of the Chinese approach to food, as well as its wit, its levity and its joy.

In ancient China, food was not only a pleasure but a grave matter and one of the main concerns of government. Edible sacrifices made to gods and ancestors sustained the social and political order: neglect them, and chaos would surely follow. That was why the Zhou Court of the first millennium BC, according to later historians, assigned more than half its staff, or two thousand people, to matters related to food and drink. There were dieticians and chefs; game hunters and butchers; meat-dryers and turtle-catchers; picklers and icehouse attendants. Some were responsible for preparing sacrificial offerings, others for feeding the king and his consorts.

Political power was symbolised by the ding, a cauldron used for cooking meat for sacrifices. In the distant reaches of Chinese history, the number of ding a nobleman was allowed to possess depended on his rank. Steal a man's ding in a military campaign, and you took away his lordly authority. The ceremonial ding themselves, cast in bronze, covered in geometric patterns, were at the heart of ritual life. These distinctive cooking pots are still one of the most potent symbols of Chinese civilisation: the Shanghai museum that opened with a great fanfare in 1996 takes the form of a ding.

Sages often compared the art of government to seasoning a stew. You had to balance the different flavours, the vinegar and pickled meats, the salt and sour plums, to achieve perfect harmony. 'The cook blends the ingredients,' said the statesman Yanzi in a text compiled more than 2000 years ago, 'and equalises them by taste, adding whatever is deficient and decreasing whatever is excessive. His master then eats it and thereby composes his mind. The relationship between lord and vassal also is like this…'

Others offered serious advice in culinary terms. The Taoist philosopher Laozi, author of the Tao Te Ching, warned that governing a state was as delicate a matter as cooking small fish, while Confucius, who lived in the fifth century BC, was as cultivated in his eating habits as he was in other aspects of his life: 'his rice is not excessively refined, and his sliced meat is not cut excessively fine. Rice that has become putrid and sour, fish that has spoiled, and meat that has gone bad, he does not eat. Undercooked foods he does not eat, and foods served at improper times he does not eat. Meat that is improperly carved, he does not eat, and if he does not obtain the proper sauce, he will not eat.' In China, knowing how to eat properly has always been a metaphor for knowing how to live.

A gentle wind stirred in the trees as we passed the great red gateway, and crossed the hump-backed stone bridge into Beihai Park. Red lanterns glowed along the edge of the dark, rippling lake. We walked through a curved colonnade, beneath a roof of richly painted rafters, watching the shifting, silent waters. The traffic and general mayhem of the city were forgotten. From here, the skyline appeared mysteriously bereft of high-rises.

The emperor himself ruled by divine appointment, and his first duty was to ensure that his subjects were fed. Droughts, bad harvests and famine were signs that the gods had tired of him, and that his mandate had expired. So every spring he ploughed three furrows at the Temple of Agriculture, and every winter solstice he fasted for three days before the annual sacrifice to Heaven. This was the most solemn religious ceremony of the year. A bullcalf, a sheep, a pig and a deer were killed in the sacred abbatoir of the Temple of Heaven in the southeast of Beijing. And then the emperor mounted the great stone altar, where he made offerings of wine and food, and banged his head on the cold marble floor.

If the best food the Forbidden City itself could offer in the post-imperial era was instant noodles, I'd heard of a Beijing restaurant that specialised in palace cooking. One evening I persuaded my Sichuanese friend Xun, who was also staying in the capital, to accompany me there for dinner.

Fangshan specialises in Chinese imperial cuisine, with an emphasis on dishes derived from the repertoire of the great Man-Han banquet. When Pu Yi left the Forbidden City, four or five of the former palace chefs opened this restaurant, then on the northern edge of the lake in Beihai Park, on the advice of a former palace eunuch, Zhao Renzhai. 'There were no recipe books in those days, and most chefs were illiterate,' the manager Wang Tao told us, 'so all their skills were passed from generation to generation by word of mouth. During the Cultural Revolution, for about ten years, this place was not open to the general public, although it continued to serve political insiders; later it was opened to important state guests; and finally in 1989 to the public once again. So although the original chefs were all dead by the sixties, we have an unbroken chain of teaching and tradition that extends right back to the Forbidden City.'

Soon the grand entrance of the Fangshan restaurant beckoned. We passed the fierce stone lions, crossed a cold flagstoned courtyard lit by lanterns, and entered the dining room. It shimmered in a haze of yellow and gold, almost hallucinatory. Yellow curtains hung behind tables draped in yellow cloths and laid with yellow plates and bowls. Waitresses in embroidered yellow robes bore trays of yellow teabowls. Golden dragons curled up golden pillars, and writhed on the painted ceiling. The old-fashioned lanterns dripped with yellow tassels. It was overwhelming, this golden evocation of the imperial past. ('When I think of my childhood,' said Pu Yi, 'my head fills with a yellow mist.')

Xun and I began our meal with a selection of delicate palace appetisers. There were small blocks of a paste made from peas, subtly sweetened and ice-cold on the tongue; and slices of a roll made from sugared haricot beans stuffed with red-bean paste and crushed sesame seeds; cold meats and vegetables. Naturally, we were then offered a parade of showy delicacies: shark's fin soup, slices of gelatinous camel's foot in a dark, velvety sauce; soft-shelled turtle; sea cucumber and abalone. Some of the snacks were of particular imperial interest, like the small sesame flatbreads with a minced-pork stuffing. The Empress Dowager Cixi is said to have dreamt of these one night, only to find them served for breakfast the following morning, to her delight. Cixi is also associated with small steamed cones of maize flour: she was given these wo tou by a peasant when she fled to Xi'an after the Boxer Rebellion in 1900, and enjoyed them so much that her cooks recreated them in a more elegant fashion on her return to Beijing.

Sadly, Xun and I didn't have three days and three nights available for the full Man-Han banquet experience, so we had to content ourselves with a mere seventeen or so dishes and snacks. We emerged at the end of the evening lost in yellow, well-fed, and rather enchanted with the whole palace dining experience. But of course I was aware that the dishes at Fangshan bore as much relation to the real foodways of Beijing as the menu of a restaurant with three Michelin stars does to the diet of a dustman in Peckham. And while I was in the capital, I wanted to experience the local food at its grittiest. The secretary of the Chinese Culinary Association had told me that, if I really wanted to taste the city's street food, I should try lu zhu huo shao, which loosely translates as 'flatbread in broth'. He warned me that it was not for the fainthearted, but I brushed off his words with a breezy smile.

Over the next few days, I kept an eye out for lu zhu huo shao. And when, one frosty morning, wandering in the hutongs that run alongside the eastern edge of the Forbidden City, I stumbled across a grungy snack shop that had a sign outside advertising ths dish, as well as other local 'small eats', I strode right in and, with my usual bravado, asked them to serve me with their most important specialities. It was a decision I regretted almost immediately.

After all my gastronomic adventures, there is only one thing that I really dislike eating, and that is the digestive apparatus of the pig and other large animals. I've eaten tripe and chitterlings enough times to feel that I am not prejudiced against them -- I eat them with an entirely open mind, and still I hate them. Their textures don't bother me at all. What I find loathsome is their rank, stealthy taste, that insidious reek of digestive juices that no amount of garlic or coriander can dispel. It stirs up in me a profound, visceral anxiety that I cannot quite explain.

On that freezing morning in Beijing, the cheery staff of the café brought forth their finest dishes and laid them on the table. The steaming stench of offal rose up and engulfed me. Here was the stuff of all my worst food nightmares lined up before me in a gruesome parade. There was a tangle of slivered sheep stomach with a sesame dip; a vile mess of pig's liver and chitterlings in a thick, gloopy sauce; and a murky broth in which floated pieces of sheep's liver, tripe, heart, lung and intestine. Most ghastly of all was the proud centrepiece of the feast, lu zhu huo shao, which one of my Chinese food books renders in English as 'Boiled pig's entrails with cake bits'. Beads of oil quivered like sweat on the surface of a dismal broth that was a casket of animal extremities: chunks of purplish pig's lung, pale tubes poking out of their sponginess; pieces of stomach and liver; slices of wobbly intestine… A fetid aroma emanated from the squashy tubes and chambers. This was hardcore streetfood, fuel for the bellies of tough working men.

When I first began thinking about the emperor's banquets, I have to admit that I felt a little envious. Imagine, whenever you were hungry, being able to snap your fingers and summon a procession of eunuchs bearing seven tables laden with food! Imagine being followed at all times by servants from the Imperial Tea Bureau carrying boxes of cakes and other delicious titbits, teacups and flasks of hot water.

I felt faint and nauseous. It would have been bad enough at any time of day, but for breakfast… I found myself reverting to the kind of disdainful thoughts you'd expect of an adopted Sichuanese like me. 'The diet of these northerners is so rank and stinky! What muttony brutes they are!' I swallowed a few foul-smelling slices of gut and liver and fled to a dumpling shop across the way.

But Pu Yi says in his autobiography that he never touched the food from the main imperial kitchens. Those thirty dishes had all been prepared long in advance, since they had to be ready to be whisked into the imperial presence at a moment's notice. They had sat around for hours on the stoves, sagging. According to Pu Yi, the eunuchs set up these official meals some distance away from him, where presumably the fats in the thirty dishes congealed, the soups grew cold, the vegetables wilted, and the pastries staled in the open air. Some of the dishes may even have been fake: one of my sources in Beijing told me wooden roast chickens and other models were used to heighten the impression of plenty.

Meanwhile, the young emperor actually ate from a quite separate selection of dishes produced in the Dowager Empress Longyu's own private kitchen. Like the eunuchs, many of whom had their own catering arrangements, she knew better than to trust the central palace kitchens. The chief imperial cooks, according to Pu Yi, were aware that their food had not been eaten for more than a decade, since the reign of his predecessor Guangxu. Did they even care how it tasted? The food Pu Yi ordered the cooks to send to the High Consorts on their birthdays was, he says, 'expensive and showy without being good… neither nutritious nor tasty.' One can imagine the apathy, the creeping negligence of the chefs, after years of producing these untouched feasts.

The grand state banquets can have been little better. Think of food cooked in enormous cauldrons, on a vast scale, and then transported long distances across lanes and courtyards, before being laid out in front of state guests seated according to a rigid hierarchy in the drafty halls. Imagine the endless toasts, the stifling ritual. How cold and dreary the food must have become. Sometimes, it's true, they set up chafing dishes to keep some of it warm. But it was all show food, fusty and bombastic, a pageant of expensive delicacies to flaunt the wealth of the Chinese empire.

I wondered if anyone had really enjoyed their meals in the Forbidden City. It is a solemn, intimidating place, especially in winter, its beauty austere. From outside, you see only roofs and watchtowers, bounded by faceless walls and a wide, frozen moat. It looks more prison than palace, forbidding as well as forbidden. The hearts of the newly selected imperial concubines must have sunk as its gates clanged shut behind them.

The diets of the concubines were strictly regulated, like everything else in their lives. They were graded by rank: in the Qing period, first below the empress was the imperial consort, then there were two high consorts and four ordinary consorts, eight so-called gui ren (another lower rank of consort), and any number of lesser concubines. They were only allowed to eat really well when, or if, they fell pregnant, because it was thought that in normal circumstances a rich diet would breed lustful thoughts. So at other times they were assigned quotas of meat, poultry, vegetables and grain foods according to their status. The imperial consort, for example, might get 12 jin (about 6 kilogrammes) of pork and ten aubergines a month, and a chicken or duck every day; but a woman at the bottom of the heap would be given only six jin of pork and six aubergines, and a mere ten birds every month. (Imagine the bickering, the bitchiness, as the top concubine savoured her piece of succulent pork at the end of the month, while lesser concubines were left with vegetables and beancurd!) The chance to eat more richly would have been just another incentive to get pregnant, an achievement that might enable a low-ranking concubine to rise up the sexual pecking order: a secondary concubine who produced a son might even end up as empress dowager, like the formidable Cixi.

Supposedly, the emperor could have eaten anything and everything. The world was his abalone, in a golden shell. Yet, as a child, Pu Yi had no appetite. He was taken from his mother before he was three, and the grandmother who had doted on him had a breakdown when he left. He didn't see either of them again for seven years, and his father only visited him for a couple of minutes every two months. Eventually his mother committed suicide, with an overdose of opium. His wet-nurse was the only person who awakened in him feelings of empathy for other human beings, and she was dismissed when he was eight years old. The high consorts of the two previous emperors officially became his 'mothers' when he was adopted into the palace, but it was a formal relationship and he says he never knew any motherly love. The heart of the empire was a cold-hearted place. Starved of affection, Pu Yi developed a stomach ailment.

Life in the palace was ridden with filthy intrigue, whoever you were. Even emperors could be its victims, like Pu Yi's predecessor Guangxu, who was humiliated and imprisoned by the Empress Dowager Cixi after a virtual coup d'etat, and who later died in suspicious circumstances. Many of Cixi's enemies came to sticky ends: suicide, decapitation, imprisonment and exile. She disliked one of her daughters-in-law so much she deprived her of food and drink until she died, had one imperial consort drowned in a well, and was also suspected of poisoning a rival dowager empress with some tainted soup. At one point, Pu Yi himself was so terrified of being murdered that he was unable to sleep, and he says in his autobiography that theft, arson, murder, gambling and opium-smoking were common within the palace walls.

It probably wasn't just a lack of love that contributed to his digestive problems. Pu Yi's diet was tightly controlled, because the health of the emperor was paramount. 'Your Majesty's body is a sacred body,' Pu Yi remembers his mother telling him when she finally did visit him in the palace. And as Professor Luo explained to me, when we met for tea one day in a café just outside the Forbidden City, 'in those days they thought fever was a symptom of inner fire, which would be exacerbated by the consumption of rich and highly seasoned food. So whenever children in the imperial family fell sick, they were given only congee to eat, to cool them down. Of course such a diet was inadequate, and many of them, over the years, actually died of malnutrition.' Pu Yi himself describes how once 'I stuffed myself with chestnuts, and for a month or more afterwards the empress dowager… only allowed me to eat browned rice porridge; and although I was crying with hunger, no one paid me any attention.' He was so desperate to eat, he says, that he snatched a little cold pork that some princes had sent in tribute to the empress dowager, to the fury of his minders.

With Pu Yi, they didn't have to worry. Professor Luo, sipping his jasmine tea in the café, lowered his voice as he told me that the last emperor was impotent. 'One of my grandmother's closest friends was his concubine,' he told me, 'and she wrote many letters to my grandmother. In them she said how lonely and miserable she was, and made veiled allusions to the emperor's incapacities. Of course no one could speak of this openly, but his lack of "face" made him bitter and tormented, and he mistreated his wives.'

Pu Yi's sexual life was no more successful than his gastronomic life. Of course he was provided with a wife and concubine when he came of age (a mere two 'dishes', compared with the hundreds of some of his predecessors). Later, he took another consort and another wife. But sex for an emperor wasn't meant to be enjoyable, any more than dinner. The Chinese have long memories, and no one had forgotten the dissipated life of the Xuanzong Emperor of the eighth-century Tang. He fell badly in love with his favourite concubine, Yang Guifei, and when his reign collapsed after a bloody rebellion, his romantic infatuation was blamed. After that, the sexual lives of the emperors were strictly regulated. Bedmates were not allowed to stay the night, lest they exhaust the Son of Heaven. Whispering eunuchs kept an eye on things, to make sure no dangerous attachments developed.

It was the emperor's duty to feed the people, but his own personal appetites were irrelevant. 'Appetite for food and sex is nature,' the philosopher Gaozi once said. But the emperor wasn't an ordinary man, he was the Son of Heaven, and for him food and sex were political events. Eunuchs watched him eat, and they waited by his bedroom door. All in all, the last emperor was a pitiful figure. Like his ancient imperial predecessor, Shi Huang Di of terracotta-army fame, he was incarcerated in an opulent tomb, provided with endless servants, riches beyond imagining, and every delicacy in the empire. The difference was that, when he was incarcerated, Pu Yi was still alive.

Pu Yi himself confessed to a 'taste for cruelty' in his autobiography, and wrote that he abandoned his new empress on their wedding night in 1922 because he preferred to sleep alone. Though he married four girls, he said 'they were not real wives, and were only there for show [and] they were all my victims.' Rumours of homosexuality dogged him when he lived in Changchun under Japanese protection in the thirties and forties. He never had a son, or a daughter for that matter, which rather neatly solved a potential problem for the communists who took over in 1949. There were no loose ends for the Chinese to tie up, as there had been, with such bloody consequences, in Russia.