Since the 18th century the United Kingdom has been one of the largest per capita tea consumers in the world, with each citizen consuming on average 1.9 kg per year. The popularity of tea occasioned the furtive export of slips, a small shoot for planting or twig for grafting to tea plants, from China to British India and its commercial culture there, beginning in 1840; British interests controlled tea production in the subcontinent. Tea, which was an upper-class drink in Europe, became the infusion of every class in Great Britain in the course of the 18th century