As a former comprehensive school pupil herself, the author wanted to know more about the women who had pioneered comprehensive schools in England. Therefore, she chose the headmistress and comprehensive school campaigner Dame Margaret Miles (1911-1994) as the subject of a dissertation for her History of Education MA at the Institute of Education, University of London. This article attempts to rebuild the story of Margaret Miles' networks of influence from 1911-1955 and explains how she gathered ideas that she hoped to transplant into the comprehensive school system after 1955. The author then move on to examine how seeds of doubt about Miles' particular vision and comprehensive education in general were introduced to a nervous public in documentary film between 1955 and 1963. (Contains 39 notes.)