Kate Stewart

Kate Stewart, born Kate Lethbridge-Stewart and nicknamed "Tiger" by her father, was the daughter of Alistair Gordon Lethbridge-Stewart and his first wife, Fiona. (PROSE: The Scales of Injustice)

Biography
Fiona and Alistair had Kate three years into their eight-year marriage.

As a child, Kate was never told of her father's work at UNIT with aliens. She was only told that he was a military man. She would often pretend that he was off to have an amazing adventure when really she knew he was off to do boring military operations.

At the time of the Wenley Moor Silurian incident Kate was five years old. It was during this mission that Alistair realised he was an inadequate father for her. The secretive nature of his work with UNIT prevented him from being consistently present in her life. His long absences from home caused Fiona to leave him. Alistair guessed that she and Kate went off to at least initially live somewhere close to Chichester, the home of Kate's maternal grandparents. (PROSE: The Scales of Injustice)

Eventually, she grew estranged from her father. (HOMEVID: Downtime) Kate was the mother of Gordon Lethbridge-Stewart. She re-united with her father circa 1997. (HOMEVID: Downtime)

In 2004, Kate encountered Mastho, one of the last Daemons. (HOMEVID: Dæmos Rising)

Later, Kate had dropped the name "Lethbridge" when she became the head of scientific research to UNIT so as to avoid favours. (TV:  The Power of Three)

Behind the scenes

 * Kate Stewart was created by Marc Platt for the direct-to-video story, Downtime, released in 1995. Her early life was chronicled the next year by Gary Russell in the novel, The Scales of Injustice.  Chris Chibnall then showed audiences about her middle-aged life in The Power of Three, almost twenty years after she was created.
 * Whether by design or accident, casting director Andy Pryor's choice of Jemma Redgrave looks like a plausibly aged Beverley Cressman.