Hubble studied at Julian Ashton's influential Sydney Art School. A review of the 1924 student exhibition describes him as having 'considerable promise' (Evening News, 11 December 1924). He exhibited with the Younger Group of Australian Artists at Anthony Hordern's gallery in 1924 and 1925.

Hubble was a camouflage artist during WWII.

He regularly entered a portrait in the Archibald Prize from 1933 to 1942, and again in 1954, 1956 and 1957. His 1940 entry "shows Julian Ashton, one of Sydney's venerable old men of the art world; his son, Howard Ashton, who also has several pictures hung in the National Gallery; and the third generation, Dick Ashton, a marine painter of outstanding promise..." (Daily News, 20 January 1940).

During the 1940s he worked as comic artist and writer, providing stories for Frank Johnson, NSW Bookstall and sometimes self-publishing. Most of his comics work is signed 'Hub' and he particularly focused on science fiction stories.

In January 1945, he exhibited in Adelaide with a group of other Sydney artists. He is reported to be living in the country and running a farm, while practicing art. Probably from this time he worked as a sales rep, selling advertising space for newspapers, magazines and radio stations.