Why is Victorian London so appropriate for the novella, The Strange Case of Dr. Jekyll and Mr. Hyde?
Victorian-era London is an appropriate setting for this novella because it was during the latter part of Queen Victoria's reign that highly moralistic language and behavior became the social norm and expectation. Published in 1886, Stevenson's work falls squarely within this period. The Victorians were quite concerned with proper dress and proper speech, but -- most importantly -- proper conduct. Citizens were expected to repress anything improper, especially salacious desires. Sexuality, especially, was taboo. This is why Henry Jekyll feels such a strong desire to extract the part of himself that drives him to do improper things and destroy it.
For many people in this era, strict moral rules didn't actually stop them from doing "bad things," it just meant that those things occurred behind locked doors and were not spoken of. Jekyll, in trying to keep with established ethical mores of the day, only wants to actually be the morally upright doctor that he portrays to the world; however, it is too difficult to repress his urges and so he attempts to kill the part of himself that responds to those desires. Were it not for his society and time, perhaps Jekyll would not have felt so keenly the necessity of abiding by the rules; if his society did not insist on the bottling-up of any desire not in keeping with the strict moral code, then he might not have resorted to such a dangerous course of action. It is, likely, his setting which actually prompts him to feel the necessity of attempting his experiment.