Lady Margaret Pritchard (PROSE: Ghost Light) lived at Gabriel Chase in Perivale with her husband, Sir George, with whom she had a daughter named Gwendoline (TV: Ghost Light) no later than 1865. (PROSE: Ghost Light) Josiah Samuel Smith arrived at the house and hypnotised its inhabitants, making Lady Pritchard believe that she was only Mrs Pritchard, the night housekeeper. In 1881, Josiah had Gwendoline kill Sir George when he saw Light's ship in the cellar.
Mrs Pritchard was charged not only with the house's upkeep (TV: Ghost Light) but also with feeding Josiah's numerous guests that he locked away. She disliked Nimrod, for whom she deliberately caused trouble when she could, and considered Mrs Grose to be a simple and barely literate woman. Whilst she had forgotten her relation to Gwendoline, she did treat her more as a governess would than a housekeeper. She occasionally began to question what was going on with the house and its guests, but chose not to. (PROSE: Ghost Light)
In September 1881, Mrs Pritchard was tasked with feeding Redvers Fenn-Cooper. She chloroformed Reverend Ernest Matthews when ordered to by Josiah and saw to Ace and the Seventh Doctor, whose influence on Gwendoline she disapproved of. The Doctor showed Mrs Pritchard a locket containing photographs of herself and Gwendoline, making her remember who she really was and that Gwendoline had killed her husband. She hugged her daughter and they were turned to stone by Light. (TV: Ghost Light)
Mrs Pritchard believed that she knew everything that happened in Gabriel Chase, which she thought of as her house, and that Josiah was a fool to think that she did not. She did not care for Nimrod and would cause trouble for him whenever she could, having something of a malicious streak. (PROSE: Ghost Light
Lady Pritchard was a proud and handsome woman when she met Inspector Mackenzie. After being under hypnosis for two years, she had a drained, grey face which showed no emotion beyond a grim pride in her work and contempt for anything else. Her eyes were dead to the world. (PROSE: Ghost Light)