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Lady Calcula was the wife of Colonel Nasgard and the mother of Yarvell and Davros, the latter by her lover Councillor Quested. She was a senior figure in Kaled politics who lived on Skaro towards the end of the Thousand Year War between the Kaleds and the Thals. She hated her sister-in-law Tashek for knowing the truth about Davros' parentage, who in turn hated Calcula for not revealing the truth to her husband and for favouring Davros over Yarvell.
Calcula hired Tutor Magrantine to teach Davros whatever he wished to learn, planted a bomb to kill Nasgard and Tashek (perceiving them as dangers to her son), and manipulated Quested, whom she worked for as his personal assistant, to have Major Brogan arrested and executed as a traitor. (AUDIO: Innocence)
Calcula contested the terms of Nasgard's will, which stated that she would not have access to Davros's trust fund until he got married. Due to her connections with senior members of the Kaled judiciary, Calcula was ultimately successful in her attempts to have he terms of the will overturned. Prior to this, she had attempted to set Davros up with the daughter of Councillor Matros, another member of the Council of Twelve who belonged to one of the most influential and wealthy Kaled families.
She and Yarvell learned of Davros's part in the mission to destroy a new Thal weapon development facility, and afterwards tricked Yarvell into revealing her part in compromising the mission. She then drowned her in the swimming pool at their home in fury. (AUDIO: Purity)
Calcula eventually took charge of the Kaled Military Youth, with Section Leader Fenn as her assistant. When Fenn tricked her into granting him access to Davros' laboratory, then attempted to destroy his work, she turned on Davros' latest invention, exposing them both to massive doses of radiation and causing them to mutate. Before dying, she told her son to dedicate himself to destroying all who would destroy him. She mutated into a very early Dalek creature — Davros said to her, "You are becoming what we will all become. But just a little too early. Skaro isn't ready for you yet. The universe isn't ready for you."
When Davros was lying unconscious and near death after the Thals had shelled his laboratory one month after Calcula's death, he heard his mother's voice, urging him to survive and live on. Whether this was truly Calcula communicating from the afterlife, or merely a hallucination was unclear.
Towards the end of the Thousand Year War, the life expectancy of Kaled females was 52, an age which Calcula had long since surpassed by the time of her death. According to Davros, she was one of the oldest living Kaleds by then. (AUDIO: Corruption)