Tea was introduced to England in the 1650s. The botanist Sir George Leonard Staunton (1737–1801), secretary to Lord Macartney, wrote in his account of their 1792–1794 embassy to China that
from fifty thousand pounds weight, the annual public sales of the [British East India] Company in the beginning of the present century, the sales in the same time, now amount to nearly twenty millions of pounds, which is four hundred times as much as it was a hundred years ago.
The tea plant, Camellia sinensis, contains substantial levels of addictive caffeine, and tea had become the drink of choice of the British public. This situation created a trade imbalance with China, which in turn motivated the East India Company to sell opium in China while at the same time cultivating tea plants in northern India. The handsome illustration of a tea plant in Lettsom’s treatise came from a plant belonging to the Duke of Northumberland.
Staunton, George. An Historical Account of the Embassy to the Emperor of China. London: Printed for J. Stockdale, 1797.