In March 1892, when he moved to London from Bristol to edit the Schoolmaster, Macnamara was well placed to comment on the entire range of educational institutions provided by public authorities in England, with more than ten years' experience in the classroom, eight years as a headmaster and Union activist and two years on the NUT executive (which put him in line to become Vice-President, then President of the Union). He took over the editorship, he recalled in 1922, ‘consumed with the fierce zeal of the wholly convinced propagandist: “Better education for the children of the people; fairer treatment for the teacher”. I can honestly say I lived for nothing else.’

The Schoolmaster had been adopted as its official journal by the National Union of Elementary Teachers in April 1872. The year before, George Collins and T. E. Heller, both members of its Standing Committee, had concluded that without press coverage the new Union was handicapped and comparatively inarticulate. Reports in the press on educational matters appeared haphazardly. Out of their slender salaries they therefore raised capital of £500 and in October 1871 set up the Educational Newspaper Company, allotting some of the shares not for cash, but as payment in advance for journalistic or other work. With William Binns they began to publish the Schoolmaster on 6 January 1872 from offices at No. 14, Red Lion Court, off Fleet Street.