The origins of tea-drinking are lost in prehistory. Chinese mythology associates its discovery with the emperor Sin Nong, who lived in the third millennium BC. Before the eighth century AD Lu Yu was commissioned by Chinese tea-merchants to explain the merits of the drink made from the leaves of the plant Camellia sinensis in a book known as the Cha Ching.

Tea drinking spread from China to Japan by the fifth century AD. Japanese Buddhist priests studying in China are credited with bringing home the seeds of the plant in 1191. Japanese green tea, Chinese black tea and Oolong tea (associated with Taiwan and is a distinctive, partially fermented drink between black and green tea) all come from the same bush.

Shuko, the first great Japanese tea-master, wrote rules for the handling of the Japanese equipage in the late fifteenth century. A family required as many as 24 items for the preparation of tea, and the cabinet in which they kept this equipage was an important status symbol.

The Portuguese priest Gaspar de Cruz was the first European to give an account of the drinking of tea, about 1560 and tea arrived in Lisbon shortly afterwards. Dutch merchants were the first to carry tea back to Europe commercially for sale, in a shipment of 1610, and teapots were among the articles of porcelain that were imported into Europe from China in ever increasing quantities during the seventeenth century. Tea drinking became fashionable first in Holland, and in England during the second half of the seventeenth century.

After the Great Plague of 1665 and the Great Fire of 1666, Londoners took every opportunity to enjoy the fresh air of the pleasure gardens that had opened in the suburbs of the city.

Everybody knew that in order to make tea, the water had to be boiled, which made it a safe drink to enjoy.

Coffee was also being drunk in London at this time, but tea enjoyed greater favour partly because it was easier to prepare.

By the eighteenth century China tea and teaware were a feature of every aristocratic and middle-class English home.

Taxes were imposed on tea in Britain from 1689 to 1964, and also in the American colonies, but in 1773 the American merchants angrily rebelled against the charge they had to pay, throwing a shipment of tea into the sea which became known as the Boston Tea Party. In Britain itself the tax encouraged smuggling, which led to tea being brought in to Ireland, Scotland and other parts of Britain as well as by the legitimate trade through the port of London.

Tea was soon recognized as an invaluable drink for the workforces of the Industrial Revolution. It was cheap and non-alcoholic and, mixed with milk and sugar; it provided needed sustenance for people working long hours in factories.

By the nineteenth century the immense popularity of tea in Britain had caused an imbalance of trade with China, and the East India Company began to pay for its tea with opium grown in India and smuggled to China in 'clipper' sailing ships.

When this trade was curtailed by the Opium Wars between Britain and China in 1839-42, the East India Company acted on Sir Joseph Banks recommendation, made in 1788, that it would be possible to grow tea in North East India. In fact the tea had been growing wild in Assam, but until 1815 nobody knew of its existence.

The Opium clippers were adapted to carry tea, and the annual races from China to Britain became legendary.

The most famous of these was the race of 1866, in which the first three ships arrived from China in London on the same tide. The tea was unloaded in wharves along the Thames particularly at St Katherine's Dock and Hays wharf near the museum.

Indian tea could be harvested over a longer season than the Chinese and Japanese variety, and British planters introduced mechanized production that was more efficient than the traditional methods. Tea was also grown in Ceylon (Sri Lanka) from 1867.

Trade with China began falling, and the British palate became adapted to the richer, more malty Indian tea. Tea was also grown in Africa from the late nineteenth century.

The quality of the Indian leaf varies considerably according to season, and in order to keep both taste and price constant the tea companies used many different crops to make up their branded blends. Edward Bramah was trained in this tradition when he entered the tea trade in 1950.

By 1900 there were 4000 tea estates in North and South India and 2000 estates in Sri Lanka. Much of the tea was coming to the London auctions and Mincing Lane became known as the world centre of the tea trade.

During the Second World War supplies of tea were severely threatened and trade in the national drink was taken over by the government and rationed. When released from government control in 1952, the tea trade soon found itself under a new threat, instant coffee. The rapid inroad of instant coffee on sales of tea in the 1960s led to the creation of the tea-bag, making possible a much faster infusion but also transforming the flavour and nature of the drink.