Reilly's writing career, which took the form of articles for the local, national and professional press together with a handful of books, and his work as a major figure in the field of architectural education were intimately interwoven. His approach to writing had the aim of promoting architecture in general, and the Liverpool School and its students in particular. While the genres ranged from travel writing through book reviewing to cultural criticism, they had a common theme: the impact of architecture and the urban environment on people's lives. However, as Reilly noted of his journalism, ‘People laughed… because they said whatever subject was started I ended up with the Liverpool School of Architecture.’ The publications to which he contributed ranged from Country Life to Tribune. In addition to prestigious journals such as these, Reilly was not averse to contributing to publications that some might have thought too low-brow for a university don. As Reilly noted, ‘I have often noticed the lower the brow of the paper, the higher the fee.’ However, it was not until the early 1920s that Reilly's journalistic career started in earnest. It was also at this time that he published his first volume on the work of McKim, Mead and White. Prior to this, Reilly's writing output was modest and specifically targeted to raise his own profile and that of the Liverpool School of Architecture.

Early Writing 1904–1921

Reilly's writing began with various small items in the local press on matters relating to such things as the saving of the Blue Coat Hospital building and the development of the architectural teaching programme at the School of Architecture. The items were generally designed to generate interest in schemes that Reilly was either involved with or hoping to become involved with. Following Reilly's appointment in Liverpool, his first major piece was The Training of Architects, published in 1905, in which he outlined his conception of architectural training as belonging firmly within the university system. The paper acted as a means of consolidating his position in one of the few university schools of architecture then in existence, as well as providing ideas for the expansion of its sphere of influence.