Should she say to the young man (and after all he was just the same age as her own boy): "If you want to smoke, don't mind me"?
No: he seemed absolutely indifferent to her presence...

she did not wish to interrupt.
But since, even at her age, she noted his indifference, presumably he was in some way or other--to her at least--nice, handsome, interesting, distinguished, well built, like her own boy?
One must do the best one can with her report.

Anyhow, this was Jacob Flanders, aged nineteen.

It is no use trying to sum people up.

One must follow hints, not exactly what is said, nor yet entirely what is done--for instance, when the train drew into the station, Mr.Flanders burst open the door, and put the lady's dressing-case out for her, saying, or rather mumbling: "Let me" very shyly; indeed he was rather clumsy about it.
"Who..." said the lady, meeting her son; but as there was a great crowd on the platform and Jacob had already gone, she did not finish her sentence.