Ernest Alexander Stuart Watt was the third son of Scottish-born John Brown Watt, merchant and politician, and the native-born Mary Jane nee Holden. He was educated in England at Clifton College, Bristol, before entering Cambridge in the 1890s. He received a BA in 1896 and an MA in 1901. Watt returned to Australia on his father's death in 1897 and inherited a share of his father's pastoral interests. He went back to London in 1900 with a wife, Annie Weston; they had two daughters before divorcing. Watt was called to the bar at the Inner Temple in January 1905 and eventually joined a stockbroking firm. In the meantime he had published his translation of Love Letters of a Genius (1905) by Prosper Merimee.

Watt married and divorced Marie Beerbohm, the niece of Max Beerbohm before marrying Bertha Campbell, daughter of Dr. A. J. Brady of Sydney. They were to have a daughter and in 1919 Watt published To Bertha and Other Verses. Rejected for active service, Watt taught at a school in Surrey for several years before returning to Australia in 1920 as a director of the family shipping firm and a variety of other companies. He became a popular figure in Sydney society and in 1929, again divorced, married the twenty-three year old Ruth Massey.

In 1921 Watt's brother Oswald, an outstanding officer in the Australian Flying Corps in World War One, drowned and Watt's tribute to his brother, Oswald Watt (1921) engendered a close relationship with his co-editors, Sydney Ure Smith and Bertram Stevens. He was appointed director of Sydney Ure Smith's Art in Australia Ltd in 1922 and bought the New Triad in 1927, editing the magazine with Hugh McCrae (q.v.). The magazine ceased operation after one year, but Watt remained a generous supporter of Australian artists and writers. He was also an ardent advocate of cremation, founding chairman of the New South Wales Cremation Company and he both edited and revised Cremation: An Essay (1923) by J. Mildred Creed. Watt also compiled A Few Records of the Life of John Brown Watt (1920-?).

(Source: Adapted from Martha Rutledge, Australian Dictionary of Biography, Vol. 12, MUP, (1990): 410).