What is the theme in The Line of Beauty by Alan Hollinghurst?

The outsider is a theme in the story. Nick is highly intelligent and well educated, but he lacks the family and breeding required to belong in the upper class. Nick is living in the fashionable Notting Hill section of London, but he is merely a lodger with a room in the roof. Upon meeting Nick, Leo says, "And I thought I'd got myself a nice little rich boy."