Ok so I'm not sure if this is a thing. Do very well off/posh Australians basically sound English?
I got to know a girl whose family is all Australian, she lived all her life there but would Europe early. Her family are wealthy, think 3-4 houses; skiing, chalet, beach house etc. She sounds 100% English. I genuinely didn't believe her when she said she was from Sydney. She genuinely sounds like she's from southern England