A Tale of Two Cities

The two cities are London and Paris.  Both cities are "port" cities in the sense that both are on a river; London is on the Thames and Paris is on the Seine.  Often, when there are places where ships can berth, there are shady, perhaps illegal dealings going on.  These illegal dealings do not want to be seen by the light of day, so if the lamplighter does not do his job, then the shady dealings are hidden from snooping eyes.  One line says that the people cannot "endure" the lamplighter.