How does the old man know Alan's name in the story "The Chaser"?

In the story, a particular line from the text explains how the old man knows Alan's name:

An old man sat in the rocking-chair, reading a newspaper. Alan, without a word, handed him the card he had been given. "Sit down, Mr. Austen," said the old man very politely. "I am glad to make your acquaintance."

It is only after Alan hands the card over to the old man that he (Alan) is addressed by name. Now, the story does not tell us what is written on the card, but we can hypothesize that the card probably contains a message or note introducing Alan to the old man and explaining his need for the old man's help. The old man also addresses Alan "very politely" after he finishes reading the card; he tells Alan that he is very pleased to make his acquaintance. Possibly, the old man is well acquainted with and respects the person who has spoken on Alan's behalf.