Even as tea goes global, its cultural meanings vary. Professor He Mingxing of Beijing Foreign Studies University observes that Chinese tea culture has spread across East and Southeast Asia through literature and trade, such as The Classic of Tea by Tang Dynasty (618-907) scholar Lu Yu, while its introduction to the West came via missionaries, explorers and merchants.

"Today, a British and Chinese person might share tea or coffee, which reflects the blending of civilizations," he says. "But our emotional ties to these drinks differ due to our cultural DNA."

He stresses that International Tea Day is a reminder of what makes these shared moments special. "The very act of sitting together over tea is a hard-won opportunity," he says. "It reminds us of the importance of a shared future for humanity."