PERTH, Australia (AP) — British Prime Minister David Cameron says that the 16 Commonwealth countries of which Queen Elizabeth II is monarch have agreed to remove gender discrimination in the order of succession to the throne. He says they have also agreed to lift a ban on monarchs marrying Roman Catholics. Cameron told reporters in Perth, Australia, that the centuries-old rules were "at odds with the modern countries that we have become." He said the changes meant that if Prince William and his wife "were to have a little girl, that girl would one day be our queen." The Queen Elizabeth II is head of state of 16 Commonwealth "realms" including Britain, Australia, New Zealand and Canada.