Who is Brenda Last from A Handful of Dust and what is their importance?

Brenda Last is the wife of Tony Last. Her sister is Marjorie, her brother is Reggie, and her mother is Lady St. Cloud. Brenda was a social woman before she met Tony, and in the beginning, Tony even ventured into her scene in order to woo her. She functioned in a circle of upper-class shallow people, mainly women whose lives revolve around parties and trends. She is a beautiful and charming woman and it was thought that she would marry within the circle; she could have any of the top choice single men around them.