Macavity is called the Napoleon of crime as he is not the master of crimes.
he is found in a by-street or in the square.
he cannot be traced by the Scotland Yard or the Flying Squad
he was never convicted of his crimes.

to give the reader a sense of the chaos, fear, and havoc taking place

the narrator is saying that the old lady made her feel uncomfortable. you know this because they say "i found that rather irksome", "perhaps it was her being so upright and trim", and "i don't think it was that, because i thought that quaintly pleasant." hope this !

dependent clause!

example: "before the food gets cold"