She was best known as Mary-Ann De Grimston, when she was the co-founder and the primary driving force behind The Process - Church of the Final Judgement. After her husband, Robert De Grimston, was ousted in 1974, and she and Robert divorced, she continued as the effective, though concealed, leader of the group, which for some years was called The Foundation Faith of God.
During the past two decades, she was known as Mary-Ann De Peyer after her marriage to Gabriel De Peyer, who appears to have taken on the mantle of spiritual direction of the inner group at the Best Friends animal sanctuary in Kanab, Utah. Best Friends is the ultimate successor to The Process (www.bestfriends.org), although most of its staff and supporters have no connection with its earlier forms or original belief system.
See other posts in the thread on The Process for more information on her and her life.