Whereas the 18th-century mission was a miserable failure, in that it achieved none of its commercial objectives - to open new ports in China for British trade; relax trade restrictions on British merchants in Guangzhou; establish a permanent British embassy in Beijing; and secure a small island along China's coast for British use - the recent Chinese mission to London was deemed an economic success: the two sides sealed £40 billion (HK$468 billion) in contracts.

This time, however, critics accused the British government of too much kowtowing to Beijing.

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In May 2013,  caused indignation in Beijing by portraying Xi in the Qianlong emperor's imperial robe on its front cover under the headline, "Let's party like it's 1793". And although British Prime Minister David Cameron resisted the temptation to fall prostrate on his knees in front of the Chinese leader with his head touching the floor nine times (as was requested of George, Earl of Macartney, in the 18th century), he was criticised by some, including his former strategic adviser Steve Hilton, for overdoing the servility.

"I just don't understand why we're sucking up to [the Chinese] rather than standing up to them," Hilton told the BBC.

Xi was treated to 21-gun salutes, rides in golden horse-drawn carriages, red carpets and state banquets. Touchy subjects were avoided.

It was apparent that getting diplomatic protocol right remains as important in successful modern trade relations as it was during that first symbolic visit, more than 220 years ago.

Macartney, like Xi, had clear commercial objectives but in the late 18th century it was Britain, not China, that was the economic powerhouse driven by an industrial revolution and looking for new markets for its products. The British were concerned about the growing trade imbalance with China, which supplied it with silk, and then tea; Britain needed to tempt China with its own wares.

The mission was dressed up as a delivery of tributes from King George III to congratulate the Qianlong emperor on his 83rd birthday. It was hoped that a highly capable diplomat such as Macartney could negotiate on commercial subjects once he had his distinguished feet under the Qing court's table. Instead, the tactic bred only confusion and distrust. The emperor was initially flattered by the gesture and accommodating to his guests, but became increasingly annoyed when the "ignorant and haughty" British delegation refused the standard protocol of kowtowing, defying the Qing tributary system.

Macartney's objection to the kowtow was that it wouldn't be fitting to offer the emperor a higher tribute than he would to his own monarch.

When he later insisted on introducing unwelcome commercial demands, such as the opening of an embassy in Beijing, the imperial patience wore thin. Ultimately, after weeks of pedantic haggling and issuing of imperial edicts, Macartney was permitted to genuflect at a symbolic audience with the emperor. He also offered to kiss the imperial hand, as he would with his own monarch, but this gesture was politely declined, and he subsequently left with no commercial deals at all.

On his long journey home from the failed mission, in 1794, Macartney described his effort as a "tedious and painful employment". It had been an extremely time-consuming and expensive one, too. The assortment of opulent imperial gifts packed in 600 separate packages had cost the East India Company £15,610, a small fortune in those days. Furthermore, the mission which left Portsmouth, England, on September 26, 1792, consisted of 95 staff plus about 700 soldiers and sailors crammed into the 64-gun HMS Lion and the East India Company merchant ship Hindostan.

It would be almost exactly two years before Macartney could brief Prime Minister William Pitt and deliver the letter that the Qianlong emperor had written to King George III, which remains the most famous put-down in the history of Sino-British trade relations: "Our celestial empire possesses all things in prolific abundance and lacks no product within its borders. There is, therefore, no need to import the manufactures of outside barbarians in exchange for our own produce."

The commercial outcome of the recent state visit could not have differed more, nor could the warm tone of the diplomatic language from both sides. The Chinese embassy in London wasted no time in listing the 28 commercial contracts clinched during the visit, including that for construction of the Hinkley Point C nuclear power station - it will be the first new nuclear plant in Britain for 20 years and the most expensive ever built. Five billion yuan (HK$6.1 billion) worth of Chinese central bank bills are to be issued in London, and there is the prospect of the issuance in London of the first yuan sovereign bond outside China; an agreement was also signed to establish an Innovation Cooperation Partnership, although details are still hazy.

No wonder the Chinese embassy in London and the British Foreign and Commonwealth Office (FCO) in China are purring with mutual congratulations and admiration.

"President Xi's visit can be described as a 'super state visit', with three supers, that is, 'super programme', 'super outcome' and 'super significance'," the Chinese ambassador to Britain, Liu Xiaoming, told guests at a reception in London last month.

When asked about the recent state visit for this article, a spokesman from the FCO speaking in Hong Kong was similarly enthusiastic: "The state visit marks the start of what is a golden era in our relationship [with China], and provided a spectacular celebration of our shared appreciation of heritage and culture, and boosted our mutual understanding."

From his London office, David Martin, of the China-Britain Business Council (CBBC), which organised the Sino-British trade summit at London's Mansion House during Xi's visit, continues the theme of shared appreciation of culture and mutual understanding. The CBBC supports Sino-British trade from 23 offices, 13 of which are in China.

"We stress the cultural side of doing business in China - typically business there is less transactional and more about relationship building," says Martin.

The power of pageantry and etiquette, however, should not be overestimated, he says.

"Look, UK pageantry and history has a strong currency in terms of soft power but shrewd Chinese business will always look at the economic factors first - no serious Chinese business person will sign a major deal just because a man in a white wig and ceremonial uniform has handed him a silver goblet of wine."

And despite all the welcoming pomp for Xi in Britain, Martin says part of his job is still to dispel media-driven myths based on an "unhelpful dichotomy" that China is either an economic monster taking over the entire planet or a dysfunctional rogue state about to go bankrupt.

As well as economically beneficial, Xi's state visit was also a chance for Britain to boost its own soft power in China, and globally, by promoting its national heritage, cuisine and traditions.

"The fact that Xi was photographed with David Cameron having a pie and a pint in a local pub reinforced the cultural links that we are promoting," says Alex Brazendale, founder of the Best of British festival being held in Hong Kong this month. "Xi's visit was a beautiful coincidence for us," he added.

The festival is using cultural icons to promote luxury British brands such as Aston Martin and Sunseeker and so boost Sino-British trade. So far the event has featured screenings of popular British movies in Tamar Park, Admiralty, and seen Chater Garden, Central, transformed into a "typical London street", complete with buskers and a fish and chip shop.

For the 1793 trip, one expert believes Macartney should have realised that his soft power would not have been novel enough to sway the Qing court.

"Macartney pulled out all the stops, much fine ambassadorial dressing up, elaborate gifts, examples of modern technology, and culture," says Professor Robert Bickers, an expert on Qing dynasty China and editor of (1993). "But because of the long relationship with Jesuit and other Catholic missionaries at the Qing court, little of this was actually new to the Qing."

Ultimately, when these "two powerful and conceited states encountered each other", there was no incentive on the side of the Qing to change the Sino-centric status quo.

"The Qing were rightly suspicious of the British, who they knew were on the advance in India and into Nepal [which threatened Qing Tibet]," says Bickers. "They had no intention of granting them any concessions. The British put on a big display, brought musicians and lots of gifts for Qianlong, all to no avail. The British were the supplicants and gained nothing.

"Last month, the British were supplicant hosts [rather than visitors]."

He points out that whereas Macartney took real musicians, Xi "brought two CDs, and his wife [well-known folk singer Peng Liyuan], as far as we know, did not sing".

It has taken both sides a long time to learn from the Macartney debacle. In 1816, attitudes had hardened and the Amherst mission to China, which sought to improve practical trading conditions in Canton (now Guangzhou), fared even worse. Lord Amherst was expelled from Beijing before he even had an opportunity to kowtow. He never received an audience with the emperor.

Professor John Carroll, of the University of Hong Kong's history department, is researching the Macartney and Amherst missions for his book , which looks at commercial affairs in Guangzhou before the first opium war (1839-42). He seeks to demonstrate that more than a century of successful Sino-British trading relations with no serious altercations has been overlooked.

"The problem, or so I am trying to argue in my book, is that the opium war has coloured our view of what were overall good times," says Carroll, referring to the century leading up to the conflict. "Neither the Macartney nor Amherst missions contributed anything significant to the commercial status in Canton. They failed to achieve their goals."

But, like Bickers, Carroll concedes that both did provide Britain with a better understanding of Qing China.

He also points out that one of the reasons Amherst was reluctant to kowtow was East India Company merchants in Canton thought such a fawning gesture would weaken their position and threaten their privileged trading status.

Carroll believes that British merchants in China had been anxious about diplomatic interference, in both cases.

"One of the themes running through Sino-British trade relations is that the men on the ground - merchants, company men or diplomats - were the ones who truly understood local conditions and the commercial realities, not the politicians in London."

He also draws interesting comparisons between those early failed trade missions and the successful state visit to London last month.

"The British are kowtowing more now than they were in 1793 because they need China even more now than they did then. That's the reality," says Carroll.

He notes that back in 2010, the British trade delegation to Beijing was not nearly so sensitive: Cameron and other politicians caused offence by wearing paper poppies - in Britain, they are worn to honour the war dead, but in China they are a symbol of the defeat and humiliation it suffered at the hands of Europe in the opium wars. ("Although, as my colleague Xu Guoqi has pointed out, the PRC officials should have known that opium is made from white poppies, not red ones," says Carroll.)

Still, even when the statesmen and diplomats make a complete hash of the political etiquette and protocol, it seems that - to an extent - trade continues regardless, and Carroll's examination of the century of Canton trade leading up to the opium wars supports this thesis. Martin also points out that the CBBC was supporting Sino-British trade efforts in the 1950s, when there were no diplomatic relations between the two nations.

"Commerce will always find a way, regardless, but when the politics is working well, the rest is much easier," he says.

Those early trade missions reveal that "to kowtow or not to kowtow" is probably not the key question at all. Then, as now, the essential requirement is trust built on mutual cultural understanding - elaborate pageantry and protocol are secondary factors.

Perhaps we should not be too hard on Macartney or the Qianlong emperor. They could hardly have researched their counterparts online or tuned in to CNN for a current affairs update.

"The world has become a small village in our own time but in the days of Lord Macartney it was still large enough to let different countries take their different courses," says historian Wang Tseng-tsai.

Even in our global village, though, there is still plenty of scope for misunderstanding and Bickers is sceptical that many in Britain understand the realities of Xi's China.

Martin, who lived in China and worked for Chinese businesses for 10 years before taking up his current post, says, "The state visit helps counter the myths and misunderstandings, but there are still some misnomers.

"Trust is the essential factor."

This was precisely what Macartney failed to establish with the Qianlong emperor.

Eventually, the British and Chinese have learned the lesson of what some scholars call the "Macartney fallacy": the belief that you can achieve successful trading relations without a wider cultural and diplomatic understanding.

And as Xi stated rather succinctly, when quoting Shakespeare in his formal address to Britain's Houses of Parliament, "What's past is prologue."