While the consumption of tea originated in China, it planted its roots in Britain. Originally, tea was viewed with skepticism from the British, and despite being avaliable all throughout London in 1659, it was not popular. It wasn't until the marriage of Charles II to Catherine of Braganza, that tea was established as a drink of the royal court. Catherine was a Portugese princess as well as a tea addict, and this helped to popularize the drink within the wealthy classes. The East India Trading Company seized the opportunity in 1664 by placing an order for 100lbs of Chinese tea.

The popularity of tea grew rapidly from then on, and it was served in over 50 coffeehouses by 1700, and 50 years later was highly favored by the lower classes. In becoming a staple drink for the masses, tea also brought a huge increase in the consumption of sugar, fueled by the slave trade. However, the increase of tea sales meant the decrease of liquor sales, and thus the decrease of liquor tax revenue. The British government led a series of acts that increased the taxation of tea in order to decrease sales, and by the 18th century, the taxation of tea import was at 119 percent. This created a need for tea smuggling, which was led by criminal gangs with brutal methods and no health standards, which often meant that the tea was being cut with anything from sheep dung to copper carbonate in order to keep the color convincing. But, the smugglers were still supported by millions of British tea drinkers. By 1784 the government had had enough, and the tax of tea was cut down to 12.5 percent, making legal tea affordable and smuggling obsolete. The idea of afternoon tea didn't come until later, in 1840, when the seventh Duchess of Bedford would get hungry around 4 pm and request a tray of bread, tea, and cake in order to keep from starving before the evening meal at 8 pm. She made this into a habit, and would invite her friends, and thus the pause for afternoon tea became fashionable. 

Citations:

L, Mary. "The History of Tea in Britain." Topic Tea, https://topictea.com/blogs/tea-blog/history-of-tea-in-britain/.

"The History of Tea." UK Tea & Infusions Association, https://www.tea.co.uk/history-of-tea.