Thanks Apple dude.
I believe it was deliberately planted, but possibly from any old source. It is in the garden of what was built as a "state house", which, in New Zealand is government housing.I believe that each house had two fruit trees planted at the time they were built.We also have a peach.

This page shows the family tree for the Pacific Rose.

I would like help to identify a plum tree on my property in New Zealand. I cannot find a similar plum on-line here or on other sites. It was planted about 60 years ago ~1952 Clingstone Red blush to light red skin when fully ripe with occasional golden sunburn tint Thin skin Only a very slight "bloom...