Helen Stoner traveled to London by train and dog-cart.
Watson finds Holmes with a “lady dressed in black and heavily veiled.” She is very frightened, with eyes like a “hunted animal.” She is the new client.
Her features and figure were those of a woman of thirty, but her hair was shot with premature grey, and her expression was weary and haggard.
Holmes comments that she came in by train, and she is surprised. She asks him if he knows her, and he explains how he deduced her method.
“No, but I observe the second half of a return ticket in the palm of your left glove. You must have started early, and yet you had a good drive in a dog-cart, along heavy roads, before you reached the station.”
Of course, Holmes likes to impress people with his observational skills, but these skills also help to set clients at ease because they realize that he is the right detective for them. If he can see how she got to London just from her clothing, he should be able to solve the murder.
Of course, Holmes is able to determine that Dr. Roylott murdered her sister.