We sent our DD to an Anglican Highschool that introduced a boy's boarding dormitory in her second year there. It was across town so no high jinks etc. It is an interesting situation: All girls high school, all boys high school. Under the same umbrella i.e. managed by the same admin... only the senior students in years 11 and 12 have mixed gender subjects. DD had been to all-girls schools since she was in pre-school and she adapted well to sharing the class with boys in year 11. We were all quite happy with the arrangement.

BTW ALL non-government schools are called "Independent". Some Independent schools are Catholic, some Anglican etc. Anglican ones are usually more expensive than Catholic.