[1] He was educated at Fort Street High School, the University of Sydney (BA, 1929), where he won first-class honours, the medal in English and the Wentworth travelling fellowship.
[2] Awarded grants by the Commonwealth Literary Fund in 1971 and 1972 to prepare an edition of the letters of Norman Lindsay, Howarth returned to Sydney.
Through his role editing Southerly, and as a literary critic for The Sydney Morning Herald, he influenced the development of Australian literature.
[4][1] He became an authority on Slessor, and concentrated research into Jacobean dramatist John Webster, with the intention of publishing a book about him, which did not eventuate.
On 12 November that year at the registrar general's office, Sydney, he married Lilian Irene Shephard, née Flynn, a clerk and a divorcee.