Significantly, dusk is described as the hour of the defeated by Norman Gortsby. It is the hour of "gloaming" that brings out those who suffer fallen fortunes or lost hopes. They come at dusk to avoid the scrutiny of those who wonder what has occurred, for it is the time that they will not be noticed. Many of the people who come out at this time have lost money, loves, or position, so they appear when they will be little noticed.
Thus, as Gortsby sits amid this milieu of discouragement and defeat, there is an older gentleman on the other end of the bench. After a time, he gets up and leaves so that the bench is vacated. Shortly, however, the young man who tells the tale of misfortune joins Gortsby on the bench. The cynical Gortsby doubts the young man's story about leaving his hotel for a bar of soap and not being able to find his way back, because the speaker does not have the visible proof of the veracity of his story; namely, the soap. Even when the young man feels his pockets for the soap, Gortsby doubts him. So, the young man "flits" away down the path.
As he, too, rises to depart, Gortsby sees on the ground a bar of soap, which has evidently fallen from the pocket of the young man. Gortsby picks it up and hurries after the young man. "The important witness to the genuineness of your story has turned up," Gortsby tells the young man, who hastily pockets the soap. In contrition, Gortsby offers the young man some money with his card so that the money can be returned. With a "catch in his voice," the young man says, "Lucky thing your finding it."
Returning to his bench, Gortsby congratulates himself on catching up to the young man, but he chides himself, "It's a lesson to me not to be too clever in judging by circumstances." Of course, the irony to the ending is that the old man returns to search for his cake of soap; Gortsby learns that he has been tricked after all and his first judgment was the correct one. Indeed, Gortsby does belong on the bench in the twilight, "the hour of the defeated."
The young con man either invented the story about the lost hotel or else he learned it from some other con man. He seems to be a novice. He should have bought a cake of soap in order to be able to produce it if someone like Gortsby should ask. No doubt the fledgling con man will keep a cake of soap in his pocket in the future--and he won't even have to buy one because Gortsby made him a present of one along with a sovereign.
The con man is operating at dusk. This is probably because it is not safe to engage in criminal activities in broad daylight, especially in a public park. The streets were patrolled on foot by uniformed policemen. The young man's hard-luck story is intricate and full of suggestions. The part about going out to buy a cake of soap suggests that the con man comes from a wealthy background. He is used to the best. He can't tolerate the kind of soap that is furnished in hotels. We don't know what kind that was, but we do know the kind of soap that is furnished in most motels these days. You get a little sliver wrapped in paper. It seems barely enough to last through a shower. In Victorian England the hotel soap may have been even worse. Instead of furnishing new soap for each new guest, the hotel might have provided a single cake of soap that stayed there until it was used up.
It is important to the con man's story that he should be presenting himself as a country gentleman, someone who does not need money but is only temporarily embarrassed and needs a small loan. He talks about being a complete stranger in London, about traveling in foreign countries, and some of the words he chooses suggest that he has been to elite schools like Eton and Oxford. Gortsby lends him the sovereign because he has gotten the impression that this young stranger might become a valuable acquaintance. Gortsby can imagine being invited down to the young man's home for shooting, being invited to dinner to repay him for his generosity, and being asked to show this aristocratic newcomer around London.
What is intriguing about the story of the lost hotel is that it is designed to extract more money from victims than a simple, straightforward request for a handout. If a panhandler asked people for money, he would be lucky to get as much as a shilling along with numerous rejections and a bunch of pennies and half-pennies. Gortsby gave the con man a sovereign, which is a coin equivalent to a pound. There were twenty shillings to a pound and twelve pence to a shilling. A beggar (like the man depicted in the Sherlock Holmes story "The Man with the Twisted Lip") would have to accumulate 240 big copper pennies, or 480 smaller copper half-pennies, to make up one pound.
Literally speaking, the role of the soap is that it fools Norman Gortsby and makes him give money to the young man.
The young man says that he has forgotten which hotel he was staying in (he had just checked in, he says, and gone to buy some soap for himself). He says he needs money to tide himself over until the next day.
The young man can't produce any soap, though, so Gortsby disbelieves him. Then Gortsby finds a bar of soap on the ground and goes to find the young man. After he gives him money, he finds out the soap actually belonged to an old man who had sat at the park bench with Gortsby before the young man came.
Symbolically, I think that the soap represents fate and luck. It was just lucky for the young man and unlucky for Gortsby that the soap happened to be there.