You could be onto something with the aristocracy. Hyacinth, like many middle class people, was trying to imitate aristocracy, which is wealth, but you're quite right, it's more than just wealth it's elitism. That's where the old money/new money clash comes in. New money doesn't have the family connections or the knowledge and traditions that come with the aristocracy.

The aristocracy don't attempt to separate themselves from the commoners. They will happily sit in the country pub chatting to the locals where the upper middle class think they're too good for that. New money often tries too hard and separates itself from the commoners while aristocracy is confident in their place. They keep the respect of the people because of that. You can imagine it going back to the time when they were the masters of the land and productive people on their land made them wealthy, so a good Lord was usually one that was good to his people too.

The actor, Robert Lyndsay, is from the town I was born and raised. He didn't leave when he gained fame and wealth. Ron Haslam lived around the corner from where Shaun lived. They were small town people and didn't get harassed for their fame by the locals and they didn't treat them any differently.