London is reversable: it hides its dark side which comes out only when night comes on. London of day light is quite different from that of the night.
It is especially well noticed in characters that act on morning & evening stage, & the events taking place there. All the characters can be divided in two categories, two separate worlds of day & night, light & darkness, white & black, kind & evil.
Serious & dramatic events are acted in night: almost all the characters are born & die in night, night is the scenery of the mysterious crime in “Burnaby Rudge”, & Nancy is murdered just before the sunrise.
Most of the events we can see in the morning are, on the contrary, comic, such as conversation between Mr. Pickwick & Mrs. Bardle, his mistress.
The same is with the characters. Even the negative ones appearing in the morning are mostly comic & funny & unable to bring serious harm, such as Alfred Jingle (“The Posthumous Papers of the Pickwick Club”), Artful Dodger & his friend Charlie (“Oliver Twist”).
But night scene belongs to another sort of criminals, burglars & murderers, cruel cowards, their masters & servants.