Who is Doris Waterman (Dos)?

Dos is Beryl's friend from boarding school. Even after Beryl leaves, they remain in contact. Dos informs Beryl about Emma's material situation and Emma's relationship with Beryl's father. She also serves as a sounding board during the first part of Beryl's relationship with Jock and gives her the type of advice any teenage girl following the social norms of the time would give.