Get your facts strait and don't be fooled by the Chinese propaganda. Great Britain was never involved in any trade with China, let alone opium trade. It was British East India Company.
East India Company was a joint-stock company that was formed initially for pursuing trade with the East Indies, and later it ended up trading with the Indian subcontinent and China.
Opium has always been in high demand in China. Chinese first came to know about opium through the merchants who traveled on the silk road. Opiums was imported from as far as Turkey and Morocco for domestic consumption in China. Since opium was procured from far away places, their costs used to be too high and only the Chinese Emperor and their officials could use it.
Later the Chinese Emperors sent many expeditions to neighboring countries to trace the origin of opium and find out if they could be viably produced in China itself. During the Tang dynasty the emperors sent a person named Xuanzang to India to smuggle the opium plant. His cover was very simple: acting as a Buddhist monk he was to travel to India and bring the secret of opium cultivation to China.
Xuanzang did succeed in smuggling opium plants from India but China's climate was not favorable for opium cultivation. So they kept on importing opium from India, Afghanistan and many other countries.
At some point of time during the 18th century, British East India Company had gained full control over all trade in India, including opium. Chinese Emperors were unwilling to pay the price that the East India Company demanded and still wanted the opium. So they started smuggling opium out of India through illegal routes. British East India Company objected to this illegal trade which ultimately resulted in a series of wars with Chinese called Opium Wars.
Remember. . . whenever there is demand, supply follows, and there will be several people who would like to adopt illegal and unethical means that Chinese did. China wanted to bring down the price of opium by not paying royalty to East India Company.
Unfortunately China has still failed to learn the crucial lesson. They are still trying immoral and unethical trade practices. Majority of counterfeit and pirated products are made in China. If NIKE chooses to get their shoes made in China, the Chinese manufacturers will steal their design to make cheap knockoffs and sell them under the same brand name.
Live and learn . . . and most important, don't believe the stories that Chinese spin doctors will tell you http://news.bbc.co.uk/2/hi/7783640.stm