[5] His unit's major, Tom Inglis Moore who was working with the Australian Army Education Service during World War II,[6] encouraged him to write[7] and read American poetry.
[8] Following his war service, Vallis enrolled in a Bachelor of Arts at the University of Queensland, studying philosophy and English.
[11] Vallis would be a writer-in-residence at the Australian Writer's Studio in Venice, Italy, organised by Bernard Hickey.
[5] He toured Queensland reciting his and others poems, and invited poet and friend Judith Wright to visit the University to give poetry sessions in the mid 1960s.
[14] Vallis was a member of a distinguished group of poets and writers, including Judith Wright, Gordon Fleet, David Malouf, Arthur Prior and Ken Hamilton.
[4] Vallis and Wright had a longstanding friendship[3][15] and he sought to have her work gain the respect he thought it deserved, especially in regard to the creation of the literary journal Meanjin.
[16] In 1958, Vallis' friend, Kathleen Campbell-Brown[4] encouraged him to seek out architect Karl Langer to design a home for him in the suburb of Indooroopilly.
The house would be inundated during the 1974 floods of Brisbane, and would be raised and moved to a higher elevation after the clean-up by a group of his friends.
[11][18] After his retirement from the University, Vallis taught a history of opera subject to students of the Queensland Conservatorium of Music.