Katherine Laird "Ka" Cox (1887 – 23 May 1938), the daughter of a British socialist stockbroker and his wife, was a Fabian and graduate of Cambridge University.

[11][12] 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.

[12] In 1906, Ka first encountered the Bloomsbury Group, attending some of Vanessa Bell's Friday Club fine arts discussions at Gordon Square.

She was said to be an aesthete, wearing diaphanous clothing with Peter Pan collars, "a miracle of poise, maturity and charm", who appealed equally to women and men.

She made her own clothes, and Gwen Darwin describes her "standing on the very edge of the cliff, her crimson skirt whirling in the wind, her head tied up in a blue handkerchief, and the gulls screaming below".

Brooke was also a member of the Cambridge Apostles, and after graduating in 1909 had taken up residence in nearby Grantchester, switching to English Literature and continuing his association with the university, working on a dissertation.

Ka became part of Brooke's circle, which also included Jacques Raverat and Gwen Darwin, a group that coalesced around him from 1908 till his death in 1915, and which later came to be dubbed the Neo-Pagans.

[17] The group started to form in early 1908, when Rupert Brooke began putting together a production of Milton's Comus for performance in July.

Ka, together with a number of other young women, were drawn in to work on the costumes, while Brooke started to draw up rules, such as asking them to forswear engagement or marriage for six months.

She made his clothes for him[f] but like many of the women in Brooke's life resisted a physical relationship, initially[17] but eventually she yielded to him by March 1912.

[10][17] Some light on this complex relationship is provided in Gwen Darwin's unfinished novel (started in 1916 and set in 1906) in which she depicts Ka as a character named Barbara.

There were at least five other women in Brooke's life at this time, Phyllis Gardner, like Gwen Darwin, an art student at the Slade, the actress Cathleen Nesbitt,[5] Elizabeth van Rysselberghe, daughter of the Belgian artist Théo van Rysselberghe,[37] Lady Eileen Wellesley,[38] daughter of the 4th Duke of Wellington, and during 1913 a Tahitian woman named Taatamata.

[41] Like the others, Ka continued to receive correspondence from Brooke[g] right up to his death,[30] the last letter poignantly beginning "I suppose you’re about the best I can do in the way of a widow" (10 March 1915).

[47] After meeting Ka, who was five years her junior, Virginia described her as being in "the heart of young womanhood", "Miss Cox is one of the younger Newnhamites...She is a bright, intelligent, nice creature; who has, she says, very few emotions".

[48][49] The Stephen sisters dubbed Brooke and his energetic outdoors circle as "Neo-Pagans", Virginia at least seeing them as a viable rural alternative to Bloomsbury.

[59][60] After the war, Ka married William Arnold-Forster, a naval officer, in 1918 and they moved to Cornwall, living in a large house called "The Eagle's Nest" at Zennor,[l] on the coast near St Ives.

[61] Her husband was active in the Labour Party, where he worked on international relations, publishing and speaking extensively on peace and disarmament.

Ka died suddenly on 23 May 1938 while her husband was away on a peace mission in North America and her death has been surrounded by many myths and legends, largely involving Aleister Crowley and witchcraft.