Our Queensland State Flag, like all other State flags in the Commonwealth its a defaced Blue British Ensign with the State Emblem of Queensland. The State Emblem is the Maltese cross with a British Crown super imposed over the top.
The history of the State Emblem is a funny story because it's part of the example of how the Colonial Office told Queenslanders what was good for Queensland. The early Queensland colonists in proposing the new colony suggested the State Emblem should be the profile of Queen Victoria (similar to the coin on Australian coinage). The Colonial Office informed the colonists that the emblem would be too hard to reproduce and then decided Queensland's State Emblem would be the Maltese Cross with the Crown on top. They reached this decision because the Maltese Cross was Queen Victoria's preferred form of the cross.