"Dusk" seems an appropriate title for this story. The author emphasizes that it is the time of day when people whom he describes as "defeated" come out because they are ashamed to be seen in the daylight.
The wanderers in the dusk did not choose to have strange looks fasten on them, therefore they came out in this bat-fashion, taking their pleasure sadly in a pleasure-ground that had emptied of its rightful occupants.
Dusk is the only time during the working week when the Norman Gortsby will be able to lounge on a park bench. He is not a gentleman of leisure but a young man making his way in the world. He probably has a fairly good job and gets off work around five, thus having a couple of hours to sit in the park. It is important to the story that the loss of a sovereign will be painful. In Saki's day a sovereign was a week's wages for an ordinary clerk.
Notice that Saki has to suggest that Gortsby can only see people's faces in glimpses.
He had failed in a more subtle ambition, and for the moment he was heartsore and disillusioned, and not disinclined to take a certain cynical pleasure in observing and labelling his fellow wanderers as they went their ways in the dark stretches between the lamp-lights.
People passing between the lamp-lights are shadows, but their faces are distinguishable in the illuminated zones. Dusk is also the time when predators come out. They benefit from the dusk in at least two ways. They can't be recognized by the police who patrol the London streets on foot, and if they are successful in fleecing someone like Gortsby, he won't be able to recognize them again. Obviously, the park would be a good hunting ground, and they want to be able to return to the scene of the crime.
Body language is eloquent. A typical park bench is about six feet long. If a man or woman sits at one end or the other, an open space of about four feet is an invitation for someone else to sit. But a person who didn't want to share a bench might sit right in the middle, leaving a tight squeeze of only about two feet on either side. This kind of body language would express a wish to be left alone.
Gortsby obviously doesn't mind sharing his bench with strangers. He must enjoy talking to people, and he must have heard a lot of appeals from panhandlers and hard-luck stories from grifters. At that time of evening, however, it would be hard to see their faces. The elderly gentleman and the young man are never given names, which makes them seem like shadowy figures whom Gortsby is unlikely to recognize again.
The title "Dusk" and the description of the setting as dark and a bit sinister, illuminated mainly by lamp-lights, help to create the mood of sadness and loneliness which permeates the story. It is a cold, cruel world. Gortsby must be unmarried. Otherwise he would go home to his wife. The young stranger who tells him the story about losing his hotel must recognize Gortsby as a potential victim, sitting alone at one end of the park bench, idly watching the passing parade.
It seems possible that the elderly gentleman is another con man who might have been planning to tell Gortsby the same story about a lost hotel. But being older and more experienced, the old man might have actually brought a cake of soap and left it there with the intention of coming back to look for it and using this as an excuse to start a conversation.
The world is full of predators. How can one recognize them in the dark? Whom can you trust in this wicked world?