cake of soap in his pocket. Gortsby learned a lesson from him, but he also learned a lesson from Gortsby. In the future the young man will be carrying a wrapped cake of soap--and he won't even have to buy one because Gortsby made him a present of the one he found on the ground by the bench.

It seems possible that the young trickster did not invent his hard-luck story by himself. He may have been victimized by some other con man with that story in the first place. If he fell for the story and parted with some of his money, he might have reflected on the experience and decided that he could try it out himself. We learn a lot of things by imitation. We get our academic education in school, but we get our street smarts in the School of Hard Knocks. 

Jim Thompson wrote a very entertaining novel about con artists titled The Grifters. The novel and Thompson himself are both covered by eNotes (see reference links below). Thompson obviously knew a lot about his subject. One of the things he emphasizes is that young con men will tend to learn from older professionals, usually by working as their assistants before branching out on their own.

The story about the lost hotel may have been circulating among British con artists for some little while before Gortsby fell victim. It seems at least possible that the "elderly gentleman" who lost the cake of soap is a con man himself and might have even cheated the young con man out of money at some earlier date--which would explain where the younger man got the story of the lost hotel. 

The role of the young man, in Saki's short story "Dusk," is to prove Norman Gortsby's thoughts on those who come out in the dusk. Norman believes that

Dusk, to his mind, was the hour of the defeated.

Essentially, Norman is out at dusk. While readers may not immediately consider that Norman may be one of the defeated, the young man proves that he is.

In order for one to be defeated, another person must succeed. The young man is able to get money out of Norman, the one thing that he seems to be out looking for (given his story). The young man, upon approaching the bench, may have seen the soap. The soap, then, gives him a perfect ally for his story. Norman can only believe the story after finding the soap.  In the end, the soap did not belong to the young man. It was simply used to get the young man what he desired.

The young man's role is explicit. He serves as the catalyst which proves Norman's thoughts on those who come out at dusk.

In the story "Dusk," the young man is plain lucky. When he cannot produce a bar of soap, Gortsby does not believe his story. The young man tells a story of forgetting where his hotel is. He claims that he went out to get a bar of soap and a drink. Upon returning to his hotel, he forgot the location and the name of the hotel. While telling this story to Gortsby, Gortsby doubts the young man's story because he cannot produce a bar of soap. Realizing that his story cannot be corroborated, the young man walks off in disappointment.

Then Gortsby finds a bar of soap under the park bench. How lucky can the young man be? Now, Gortsby changes his mind about the young man's story. Gortsby now believes the young man's story. Gortsby chases after the young man and gives him a loan of money and the bar of soap.

It is a stroke of luck for the young man. It just so happens that  the old man just happened to drop a bar of soap. The old man, who sat on the bench before the young man sat down, just happened to drop a bar of soap. When the young man sits down to tell his story, he just happens to add the part about purchasing a bar of soap. It is nothing more than a coincidence. It is sheer luck. The young man had not seen the bar of soap on the ground. He walks away dejected when Gortsby asks about him having a bar of soap to prove his story. It is clear that he had not seen the bar of soap on the ground. Therefore, it is plain luck that Gortsby just happens to see the bar of soap on the ground, under the bench.

Only when the old man comes back looking for his bar of soap does Gortsby realize he has been scammed. By this point, the young man   is lucky for he is long gone, on his way with Gortsby's loan--money Gortsby will never see again:

As Gortsby walks back, he passes the bench where he had been sitting. He notices the old man who had also been sitting there earlier. The old man is now searching for something. When Gortsby asks if the old man has lost anything, the man replies, “Yes, sir, a cake of soap.”

My impression of the young man is that he is very bold and temperamental. He must be smart to be able to memorize the complicated story he tells Norman Gortsby. It is so complicated that it is hard to remember the details or to understand what he is after.

He says he just came to London from the country intending to stay at a hotel which he didn't know had been torn down. He had to find another hotel, and then, being unfamiliar with the big city, he lost his way when he went out to buy a cake of soap and couldn't find his hotel again. The cake of soap is a nice touch because it characterizes him--at least in his story--as an affluent country gentleman who is used to having the best of everything. One would think that the soap supplied by a good hotel would be satisfactory for most people--although the hotel soap in London hotels a hundred years ago might have been the same kind of slippery, parsimonious little bars we get in American hotels and motels today.

He tells Gortsby:

"I'd forgotten to pack any and I hate using hotel soap."

He seems a very forgetful young man. He loses his hotel, forgets to pack his own soap, apparently neglects to make reservations at the Patagonian Hotel where he had originally intended to stay, and then loses the cake of soap he went to so much trouble to buy. Yet he has his story down pat.

What the young man implies that he needs is enough money to get him into yet another hotel for at least one night, until he can contact his "people" in the country and have them give him the address of his second hotel. When he found that he wouldn't be staying at the hotel that had been demolished, he sent a letter to his relatives giving them the address of the alternative hotel. His relatives know where he lives but he doesn't. He sounds like someone who stumbles through life making an endless succession of mistakes. Yet perhaps this is intended to characterize him, in the eyes of people he hopes to swindle, as the sort of gentleman of leisure who needs a secretary and a valet to take care of trivial matters for him.

He seems smart enough, but I couldn't call him lucky. He was just lucky that one night--and that was by the weirdest coincidence of the elderly gentleman losing the cake of soap by the bench. Saki describes him as a young man. Youth is an important element. He is apparently just starting out on a career as a confidence trickster and hasn't yet developed his craft sufficiently. He is trying to extract money from strangers by gaining their "confidence," but he hasn't had enough experience to develop his own "confidence." He might be called the un-confident confidence man. But he is learning. In the future he will carry a cake of soap in his pocket, but he won't bring it out and display it unless the "mark" should question him about it, as Gortsby ends up doing.

"Of course," said Gortsby slowly, "the weak point of your story is that you can't produce the soap."
"I must have lost it," he muttered angrily.

He displays a lot of anger for a confidence man, whom one would expect to be smooth. He is not angry about losing the soap, because he never had it. What he is angry about is that he has wasted time telling his complicated story to a cynical young man who obviously never had any intention of lending him money and might not even have any money himself. He expresses anger when he plops down on the bench and more anger when he gets up to leave. Who would want to lend money to such a volatile stranger?