I know we are a little bit luckier in our climate than you lot on the north island, but to have a daff out in flower for xmas must take some beating. No special treatment and all on its own and in a group of last years mixed bulbs that were planted in a corner that was empty in early november.
I do not know what variety, but I should think it was a dwarf type, unless the plant growth is stunted.
I also had a shock when the prunus subbirtella all of a sudden burst out in bloom, but after reading the label it is the autumnalis rosea which comes out from nov. to march. I did not realise that I had that variety and would recomend it to anybody that has the space and likes a bit of winter colour.
I am going to try grafting some of it into a spring flowering variety and see if I can get it to flower tice a year.