Flint is one of Australia's most prominent constitutional monarchists, in opposition to Australian republicanism. His book, "The Cane Toad Republic", was used in the 1999 referendum campaign. That was followed in 2003 by "Twilight of The Elites", which supported Australia's constitutional arrangements and the role of the Australian Crown. Flint has been National Convenor of Australians for Constitutional Monarchy since 1998, and a board member of the Samuel Griffith Society. He is a patron of the International Monarchist League in Australia, which supports and advances constitutional monarchy.