Quote ="reffy"Property Of (his/her) Majesty.....deported convicts.'"
It's actually a shortened version of Pomegranate, which is believed to have been an Australian attempt at Rhyming Slang and also because pale skin immigrants turned the same colour as said fruit when out in the sun for too long.
It is not either Property of Mother England nor Prisoner of Mother England, and is accepted as non-offensive in Australia (which is not to say it isn't)
Aussie, same as Paddy, Sweaty, Taffy & Kiwi are all common names for 'stralias, Irish, Scottish, Welsh or New Zealanders. Only the Astralians refer to Brits as Poms, whilst Kiwis refer to them as Pakeha