Carla Langer

Carla Langer was the ex-wife of Paul, and mother of Clyde Langer.

Profile
Carla's former husband left her for her own sister and vanished completely from their lives. (SJA: The Mark of the Berserker)

Her mother (more likely than her mother-in-law, since Clyde mentioned not knowing his father), Clyde's grandmother, lived at Lavender Lawns and tipped off Clyde on strange happenings transpiring there (SJA: Eye of the Gorgon) During the 2009 Dalek invasion she and Clyde were away together. (DW: The Stolen Earth)

Behind the Scenes
In Clyde Langer's first appearance in Revenge of the Slitheen, he revealed a small part of his family history and mentioned that his father had left him.