Katherine Laird Cox, known as "Ka",[a] was the daughter of Henry Fisher Cox (1848–1905)[b] and his wife, Jane Thompson Laird (ca. 1852–1900). Cox was a wealthy stockbroker and Fabian. Ka was raised in "Hook Hill", a house her father had built at Hook Heath, near Woking, Surrey in 1893. Ka was the second of three daughters, her sisters being Hester Laird Cox and Margaret Anna Laird Cox. Ka's mother, who had been in poor health, died in 1900 when Ka was only 13. Her father later remarried and had two further daughters, Winifred and Sydney, by his second wife Edith. She attended St. Felix School, Southwold in Suffolk, "a school where girls are treated like sensible creatures", then considered a feeder school for Newnham College, Cambridge. Ka's father died suddenly on 19 January 1905, when she was 18, with an estate of ₤22,000, leaving her and her sisters financially independent. Ka was left in the slightly unusual position for a young woman of her class and time of now being free to live, travel and love, as she pleased. On her father's death, her stepmother sold "Hook Hill" and moved into a smaller house, further down the hill, called "Hook Hill Cottage" (1904), for a further ten years.