Professor Sir Godfrey Thomson is one of the key foundational actors in the history of the educational sciences in the UK. At a time when educational studies and the study of educational psychology were very closely linked, in the decades of the mid-twentieth century, Thomson was a crucial figure in education research. He is known for his work on intelligence, factorial analysis and the validation and production of intelligence tests (the Moray House tests). However, he viewed himself as a teacher in his work as a professor at the University of Edinburgh and as director of Moray House teachers' college. He managed closely an ambitious plan to develop an advanced school of education, combining the university department of education, teacher training and a demonstration school, and supervised and taught on many of its courses. This paper is based on a unique resource, an audio recording of Thomson teaching in the early 1950s. It considers the distinctiveness and the research value of this audio source in relation to complementary oral and documentary sources. (Contains 2 figures and 43 footnotes.)