Australian English - Cockney and the Irish

Australian English is very non-rotic variety, just like Cockney in this regard. The influence of the Irish on Australian English isn't as obvious as the British are. In the late 1700s and early 1800s, most Irish people actually spoke Irish Gaeliga or they spoke English as their second language. This means that most of the Irish prisoners who were sent to Australia probably spoke Irish as their first and possibly only language. And thus their children would have been forced to learn a British variety growing up.