Gwendoline was born no later than 1865 (PROSE: Ghost Light) to Sir George and Lady Margaret Pritchard of Gabriel Chase. She had fond memories of riding into Perivale with her father, followed by their barking dogs.
Josiah Samuel Smith had arrived at the house by 1881 and warped everybody's memories, making Gwendoline believe that she was his ward and that her mother was the housekeeper. When Sir George saw Light's ship in the cellar, Josiah made Gwendoline kill him before making her believe that he had gone to Java. (TV: Ghost Light) In August 1883, Gwendoline and her "uncle" once made a trip to see the Royal Italian Opera perform Aida at Covent Garden on one of Josiah's field trips, where they were seen by Reverend Ernest Matthews. (PROSE: Ghost Light)
In September 1883, Gwendoline met the Seventh Doctor and Ace when they visited the house. As a result of the newcomers, she began to question what had happened to her parents, (TV: Ghost Light) but chose to simply believe Josiah as it was easier. (PROSE: Ghost Light) She was ordered to kill Ace and attempted to do so before she showed Gwendoline a picture of her mother, whom she recognised as Lady Pritchard. As mother and daughter remembered who they were and realised all that they had done, they embraced and were turned to stone by Light. (TV: Ghost Light)
Gwendoline liked to sing and play the piano (TV: Ghost Light) and considered some of the stuffed animals around the house to be like her best friends. (PROSE: Ghost Light) She greatly enjoyed killing people, something that the Doctor found difficult to forgive despite her hypnosis. (TV: Ghost Light) When she found herself questioning reality, she decided that she found Josiah's ideas much clearer. (PROSE: Ghost Light)