With reference to the phrase, "unlucky thing you finding it," what 'luck' did the young man have in the story "Dusk"?

The young man who has fabricated a tale in order to finagle money from someone is unable to produce a bar of soap that he supposedly has purchased so his tale holds no verisimilitude. But, after he leaves, a bar is found beneath the bench on which he has been sitting.

In Saki's satirical story, "Dusk," a young man, who has woven a tall-tell about leaving his hotel in order to purchase a bar of...

The young man who has fabricated a tale in order to finagle money from someone is unable to produce a bar of soap that he supposedly has purchased so his tale holds no verisimilitude. But, after he leaves, a bar is found beneath the bench on which he has been sitting.

In Saki's satirical story, "Dusk," a young man, who has woven a tall-tell about leaving his hotel in order to purchase a bar of soap, tells Norman Gortsby that he has forgotten his way back to the hotel where he stays, and unless someone gives him some money, he will have no place to sleep this night. However, when he cannot produce the soap as evidence of the verity of his story, Norman rejects his tale, gives him no money, and the young man hurriedly departs in anger at his oversight.

Afterwards, Norman Gortsby stands up from the park bench on which he has been, and he notices a cake of soap, wrapped in paper, under the bench on which he and the young man have sat. He hurries to catch the young man:

"The important witness to the genuineness of your story has turned up," said Gortsby, holding out the cake of soap; "it must have slid out of your overcoat pocket when you sat down on the seat."

Taking advantage of the credibility of Gortsby, who hands him a sovereign and his card along with instructions that the other can mail the money back to him, the young man says,

"Lucky thing your finding it,"...with a catch in his voice, he blurted out a word or two of thanks and fled headlong in the direction of Knightsbridge.

Norman Grotsby learns of his folly when the older man who has been on the end of the bench returns to search for his bar of soap.