In 1901 Lethaby was appointed the first Professor of Design at the Royal College of Art. This, coupled with his appointments as Principal of the Central School of Arts and Crafts in 1902 and as Surveyor of Westminster Abbey in 1906 meant that he was increasingly devoted to the academic study of the theory and history of architecture and design. He effectively ceased architectural practice around this time, though he remained an immensely influential figure through his writings and teaching. Lethaby's role as a guide and mentor to German Cultural Attaché Hermann Muthesius during his investigations into English architecture was to prove particularly significant in the light of Muthesius's later role as an influence on the early pioneers of the Bauhaus.