Born in Woolloomooloo, W. J. Miles worked for his father's accounting firm before embarking on an independent career in business. He was director of several large companies, maintaining a controlling interest in several. This allowed him to retire in 1935 on a substantial income with which he supported several causes close to his heart.
Miles was a co-founder and secretary of the Sydney branch of the Rationalist Press Association which published the Sydney Rationalist Annual. Opposing Imperial Federation with the slogan 'Australia First', he established the Advance Australia League in 1917 and contributed to several periodicals, including Ross's Monthly and Socialist.
Miles minimised his political activities in the decade before his retirement, but, after 1935, he devoted himself to secularist and chauvinistic propaganda. The first organ for this propaganda was the Independent Sydney Secularist which ran until war-time paper shortages influenced its closure in 1940. A more influential periodical was the Publicist for which Miles had employed P. R. Stephensen as literary adviser. Miles also financed the Aborigines Progressive Association and ran a small bookshop from the magazine's office. Furthermore, he supported the publication of Stephensen's The Foundations of Culture in Australia (1936) and Xavier Herbert's Capricornia (1938).
Miles suffered from heart problems for much of his life. At the end of 1941 he transferred the Publicist to Stephensen and several other supporters. Miles died in January 1942.