Londoners cross southbound over London Bridge during the evening rush hour. A young man strides along with a handset that keeps his attention, walking alongside a bus, followed by others walking out of the City of London. There has been a crossing over the Thames here since the Romans first forded the river in the early 1st Century with subsequent medieval and Victorian stone bridges becoming an important thoroughfare from the City on the north bank, to Southwark on the south where transport hubs such as the mainline station gets commuters to the suburbs and satellite towns.