Most of the “shabby” elite won’t even look at anyone from a working class back ground.. How did he ever get into a social circle that Lilian belonged too.
She is frugal...so it couldn’t been for the money and things that he could buy her.
I believe it’s explained later in the book.
Suffice to say the “shabby elite” may look down on someone from the working class, but, they won’t say no to their money.