His best known single work is The Enchanted Duplicator (1954), co-written with Bob Shaw, an allegory of a fan's quest to produce the perfect fanzine.
Along with White, Shaw, George Charters, Ian McAulay, and John Berry (an English policeman then with the Belfast force), Willis represented the influential Irish Fandom, also known as the Wheels of IF (named after the L. Sprague de Camp fantasy story and collection).
[2] Willis was known for his droll, humorous writing, especially in a column "The Harp That Once or Twice" that began in the US fanzine Quandry edited by Lee Hoffman in 1951.
Willis published the founding document for TAFF in "Hyphen 4" (October 1953) following a discussion with "the available leaders of British fandom" at that year's Coroncon.
He published one book professionally, under the pseudonym Walter Bryan: The Improbable Irish (1969), a linked sequence of mostly humorous essays about Ireland, its history and its people.