 Critchlow was professor of Islamic Art at the Royal College of Art in London from 1975 for many years.He also delivered lectures on the application of sacred geometry in architecture at the Lindisfarne Association in New York City and then Crestone, Colorado, in the United States from 1978.In Crestone, he contributed to a number of summer schools for Lindisfarne and taught alongside innovative thinkers from both the arts and sciences, including social philosopher and cultural critic, William Irwin Thompson (founder of the Lindisfarne Association), mythographer and symbolist Robert Lawlor, poet and environmental activist Wendell Berry, biologist John Todd, and environmentalist James Lovelock.