As Lamia said, I assume that Sewell would have avoided using the name Nicholas Skinner if she knew for a fact that there was an actual (innocent) cab owner in London with that name. But how do you avoid using the name of an actual (innocent) countess? I’m not sure what you can do other than make up a fake title (there’s plenty of that in “Vanity Fair”, for instance) or use an obscured real title.
Yes, that’s the issue. Making up a fake cabbie named Nicholas Skinner isn’t as obviously fake as making up a fake countess.
I wonder how the readers of audiobooks handle this.