In the novel, reference is clearly made to his own alma mater, St Aloysius' College, as the description of the fictional school, St Ignatius',  is clearly a description of the buildings and environs of the school Cronin attended.
In the novel, it is openly stated that Cronin's own educational institution, St Aloysius' College, serves as the inspiration for the depiction of the fictional school, St Ignatius', with its architecture and environment being directly based on Cronin's former school.