In "The Umbrella Man," what do the girl and her mother find out about the gentleman after he enters the pub?

The mother and daughter learn they have both been deceived about the little old man with the umbrella.
The man's deception of the woman is rather cleverly accomplished: He tells the narrator's mother that he has forgotten his wallet and he needs the fare for a taxi because he has walked too far and his "old legs" are tired. He offers to sell his twenty-pound umbrella for just one pound for the taxi-fare.
The mother feels it wrong to purchase a silk umbrella for twenty pounds, so she suggests she just give the little man a pound. She tells the old gentleman that she does not feel right about taking his umbrella. The little old man insists that she take his umbrella, saying,

But now it’s of no importance so long as I can get home and rest these old legs of mine.

The mother provides the old gentleman with the pound he desires. Afterwards, the mother congratulates herself on judging the man's character correctly. Just then, her daughter sees the man scurrying down the street. The mother decides to follow him as he dodges in and out of places where people stand. Finally, the mother and daughter see him enter a pub where he lays down the pound note given him and orders a "treble whisky," a whisky that is three shots. The daughter and her mother realize the mother has been tricked. Then she watches as the man departs. He goes to the hook where his coat is hung, but while doing so, he grabs an umbrella. He then goes out of the building with his new prize.