Who is Sergeant Barbara Havers from A Great Deliverance and what is their importance?

Sargeant Havers is a member of the CID. She is described as unnattractive, and as having no wish to present herself as such. Assigned to work with Lynley, Havers is torn between her attraction to the man, as well as her resentment that he was born to priviledge. Over the course of the novel, she gets over her attraction and comes to respect Lynley as a person.