Quarantine "yellow jack" but this was also a name for yellow fever, which probably derives its common name from the flag, not the color of the victims (cholera ships also used a yellow flag). The plain yellow flag ("Quebec" or Q in international maritime signal flags) probably derives its letter symbol for its initial use in "quarantine", but this flag in modern times indicates the opposite—a ship that declares itself free of quarantinable disease, and requests boarding and routine port inspection. Australia has perhaps the world's strictest quarantine standards. Quarantine in northern Australia is important because of its proximity to South-east
Flag of Australia 1924 agreement that the Union Flag should take precedence as the National Flag with state and local governments henceforth able to use the blue ensign. As the Union Flag was recognised as the National flag, it was considered disloyal to fly either ensign without the Union flag alongside, and it was the Union Flag that covered the coffins of Australia's war dead. In 1940 the Victorian government passed legislation allowing schools to purchase Blue Ensigns, which in turn allowed its use by private citizens. Prime Minister Robert Menzies then encouraged schools, government building and private citizens to use the Blue