Tea itself was unknown in Britain until the 17th century. It soon became hugely popular. There is a story that tea saved countless lives, because before its arrival, people drank more beer; the dirty water in this often killed them. Tea, being made with boiling water, was much safer. Whether or not this is the reason for tea's popularity, it was already a beloved national institution when the custom for afternoon tea started. This is believed to have been the invention of Anna, Duchess of Bedford, in the early 1800s. It was already usual for fashionable ladies to drink tea with their friends in the afternoon, perhaps with a cake; the duchess and her imitators made this into a small meal, with several cakes, scones and perhaps thin sandwiches. This meal is still served in many hotels and cafes in Britain, most famously the Ritz Hotel, where it is a substantial repast.
