flowing between 200 miles of solid walls; these defend a floodplain where 1.5 million people work and live.

A major maritime route is formed for much of its length for shipping and supplies: through the Port of London for international trade, internally along its length and by its connection to the British canal system. The river's position has put it at the centre of many events in British history, leading to it being described by John Burns as "liquid history".