"To carry the banner" means to walk the streets all night; and I, with the figurative emblem hoisted, went out to see what I could see.

Men and women walk the streets at night all over this great city, but I selected the West End, making Leicester Square my base, and scouting about from the Thames Embankment to Hyde Park.
The rain was falling heavily when the theatres let out, and the brilliant throng which poured from the places of amusement was hard put to find cabs.

The streets were so many wild rivers of cabs, most of which were engaged, however; and here I saw the desperate attempts of ragged men and boys to get a shelter from the night by procuring cabs for the cabless ladies and gentlemen.

I use the word "desperate" advisedly, for these wretched, homeless ones were gambling a soaking against a bed; and most of them, I took notice, got the soaking and missed the bed.

Now, to go through a stormy night with wet clothes, and, in addition, to be ill nourished and not to have tasted meat for a week or a month, is about as severe a hardship as a man can undergo.