This week Neil MacGregor's history of the world is looking at how the global economy became cemented in the 19th century, a time of mass production and mass consumption. He tells the story of how tea became the defining national drink in Britain - why have we become so closely associated with a brew made from leaves mainly grown in China and India? The object he has chosen to reflect this curious history is an early Victorian tea set, made in Staffordshire and perfectly familiar to all of us. The historian Celina Fox and Monique Simmonds from Kew gardens find new meaning in the ubiquitous cuppa. Producer: Anthony Denselow.