Question

How do people often call The London Underground?

Answer 1

Often call Tube........

Answer 2

People often refer to The London Underground simply as "the Tube." This nickname comes from the cylindrical shape of the tunnels that make up the subway system, and it has been in common use for many years. So, when someone talks about taking the Tube or using the Tube to get around London, they are referring to traveling on The London Underground.