He had an appointment with the railroad tycoon and that fellow was running late, so he let himself in to wait in the parlor.

Even back when I was a child (living in a small town) we never locked the doors. In the 1800's and early 1900's the homes had parlors which were kept strictly for entertaining visitors (the clean room). Pretty much, in the absence of any type of gizmo such as we have today, everyone played a musical instrument and it was not usual to have a piano in the parlor too.

V.