The Australian colonial 'ruling class' was predominantly Anglican even though many in the convict class and some of the lower army ranks were Catholic. There were also other protestant denominations. In the early days of the colony, in NSW and Tasmania the children of Catholic convicts and all orphans under the care of the colonial government were brought up as Anglicans. As the population grew and more Irish convicts and migrants arrived the Catholic population also grew. If you're interested there's a great summary of the Christian churches in Australia have a look at https://en.wikipedia.org/wiki/Christianity_in_Australia