David completed transition to Carol with surgery from Dr Georges Burou in Casablanca in 1972. She was in the clinic there the same time as Jan Morris. The revised edition of Approaching Sociology in 1972 names the co-author as Carol S. Riddell.
Also in 1972, she presented a paper to the National Deviancy Conference 10 on “Transvestism and the Tyranny of Gender” in which she analyses the two-gender system as a feature of capitalism – which was an early influence on sociologist Dave King who also later wrote on the sociology of trans persons.
In 1980 Carol wrote a critical pamphlet reviewing Janice Raymond’s 'The Transsexual Empire' criticizing its factual errors, its betrayal of feminist ideals and its use of masculinist ideas. This was well received and much reprinted.
In 1985 she became a devotee of Sai Baba and the Findhorn Foundation, and her later work is devoted to the sect and to the Hebrides where it is located.
- Carol Riddell. “Divided Sisterhood : A Critical Review of Janice Raymond's 'The Transsexual Empire' “. Liverpool: News from Nowhere 1980. Parts 2,3,5 reprinted in Richard Ekins & Dave King (eds). Blending genders: social aspects of cross-dressing and sex-changing. London and New York: Routledge. 257 pp. 2002; reprinted in Stephen Whittle & Susan Stryker (eds). The Transgender Studies Reader. Routledge. 752 pp. 2006.
- Richard Ekins & Dave King. The Transgender Phenomenon. London: Thousand Oaks; California: Sage. 2006: 2, 5. Excerpt online at http://www.sagepub.com/upm-data/11790_Chapter01.pdf.
- www.carolriddell.co.uk. No longer available.
- Carol Riddell. Social Self-Government: Theory and Practice in Yugoslavia. Our Generation, 1970.
- Margaret A Coulson & Carol Riddell. Approaching Sociology. Routledge & Kegan Paul, 1972.
- Carol Riddell. The Findhorn Community: Creating a Human Identity for the 21st Century. Findhorn Press, 1990.
- Carol Riddell. The Path to Love Is the Practice of Love: An Introduction to Spirituality with Self-Help Exercises for Small Groups. Findhorn Press, 1995.
- Carol Riddell. Tireragan: A Township on the Ross of Mull : a Study in Local History. Highland Renewal, 1996.
- Carol Riddell. Introducing ESOL Skills for Life Provision in a Further Education College: The Quest for Materials. University of Manchester, 2005.
- Carol Riddell. A Way Forward for Humanity: The Spiritual Basis of the Findhorn Community. 2013.