Although she was acquainted with Surrealism from her stay in Paris in the early 1930s, she visited the International Surrealist Exposition in London in 1936, and it was clear within the next two years that Surrealism was starting to impact her work more directly, primarily influenced by her exposure to Salvador Dalí. In 1939 she visited André Breton in Paris, and started working with automatic techniques in her writing and painting. By the late 1930s she was exhibiting with other Surrealists in Britain in prominent Surrealist spaces such as the Mayor Gallery. Colquhoun was active with the British Surrealist group until 1940, when she had an ideological split with Edouard Mesens who was the movement coordinator and figurehead. She married another Surrealist, Toni del Renzio in 1943 in hopes of promoting a “more authentic” Surrealism in London, but she and Del Renzio were divorced in 1947. Despite her break with the movement, Colquhoun was a lifelong adherent to Surrealism and automatic techniques continued to be the cornerstone of her artistic practice.
In the 1950s Colquhoun then emerges as a nexus of all of the major occult currents of the 20th century. She was entrenched in the Western esoteric tradition, but was also well read in Asian traditions, including Buddhism and yoga. Kabbalah and alchemy were probably the most consistent references throughout her body of work, followed by her interest in Druidry and Nature religion. She was an initiate of a wide variety of different orders representing Hermetic and Pagan traditions, including the OrdoTempli Orientis, Co-Masonry, the British Circle of the Universal Bond, the Golden Section Society, and in later years the Fellowship of Isis. Although she was unsuccessful at her attempts to become an initiate of Golden Dawn at an early stage, the Golden Dawn system of magic was clearly one of her guiding principles, and she wrote the influential account of the Golden Dawn magicians, The Sword of Wisdom published in 1975. She was also a key member of a Golden Dawn-type organization, The Order of the Pyramid and Sphinx, founded by Tamara Bourkhoun in the 1960s.
Colquhoun felt a great spiritual affinity for Cornwall and was an advocate of Cornish culture although she herself was not Cornish. The Cornish landscape and ideas about Celtic spirituality were key themes in her poetry and writings from the 1950s onward. She permanently relocated to West Cornwall from London in the late 1950s and remained there until her death in 1988.