Chrissie Jackson

Chrissie Jackson was the ex-wife of Alan Jackson and mother of Maria Jackson. Chrissie and Alan divorced not long before Alan and Maria moved to Bannerman Road, and despite the separation, Chrissie continued to take an active role in Maria's life, often stopping by Alan's house unannounced. (SJA: Invasion of the Bane) Chrissie was involved in a relationship with a man named Ivan, which led to friction with Maria, who accused Chrissie of walking out on her family; this friction reached a head when Chrissie briefly moved back in with Alan and Maria during a brief estrangement with Ivan. (SJA: Eye of the Gorgon)

Chrissie expressed a mixture of distrust and jealousy over Maria and Alan's relationship with their neighbour, Sarah Jane Smith; her instinct appeared to be confirmed when Sarah Jane was suspected of kidnapping her adopted son, Luke from another family; it was Chrissie who notified the police. (SJA: The Lost Boy)

Chrissie's personality tended to be brash and rude at times, although she exhibited tenderness towards her daughter and continued affection for her ex-husband. (SJA: Eye of the Gorgon, Whatever Happened to Sarah Jane?, The Lost Boy) She also expressed continued skepticism about the existence of alien life, despite worldwide events and her own face-to-face encounter with a Graske. (SJA: Whatever Happened to Sarah Jane?)

She defeated Kaagh by swinging the heel of her her high heel into his probic vent. Unfortunately as a side effect she was electrocuted and temporarily knocked unconcious. Maria gave her gas to knock her out that Luke developed, making her supposedly forget about aliens. However, it was later revealed that she remembered everything, yet she didn't tell Maria or Alan Jackson, as she thought they deserved a fresh start. The only one who knew that she knew was Sarah Jane Smith. (SJA: The Last Sontaran)

When Alan and Maria left, she stayed in England to marry Ivan, which Alan and Maria witnessed.

Alternate timeline
In the alternate timeline created by the Trickster, in which Sarah Jane died in 1964 and Maria was also taken out of time and space, Chrissie and Alan still divorced but Chrissie had no memory of ever having a child. Despite this and their divorce, she and Alan were still close and had a mutual friend in Andrea Yates -- the neighbour who replaced Sarah Jane in the timeline. (SJA: Whatever Happened to Sarah Jane?)