I have no idea what it might be, shrubby peonies are not my specialty and it is very difficult to identify peony varieties as there are so many of them. I like the color, but what surprises me is the fact that you write it is known to flower 3 months earlier than now, August. Considering you’re on the opposite side of the world, August would be comparable to February here and thus three months earlier to the end of of November when for sure not a single peony flower is in bloom in Europe (or the US/Canada). This means it sometimes flowers in early Winter? I thought peonies flowered mostly in October/November in New Zealand? Is it the higher temperatures during Winter you’re experiencing or is it a particularly early cultivar compared to other peonies?

I have gone back and checked photos and It has consistently flowered Aug/Sep or Sep/Oct for the last 7 years. I shifted it 8 years ago to a more sheltered less frosty position so that may explain it. Magnificent flowers but they often suffer from rot at the stem of the flower despite spraying a fungicide regularly.