High Quality Content by WIKIPEDIA articles! George Platt Brett, Sr. (1859–1936) was a British-born chairman and publisher of the American division of Macmillan Publishing. He was best known for serving as publisher, friend, and mentor of American author Jack London. Under Brett`s leadership, Macmillan became one of the largest publishers in America. Sales grew from $50,000 in 1890 and grew to $8.5 million in 1931. In 1931, Macmillan annuals produced between 600 - 700 titles.