Supply and demand
You can fly Air NZ MEL/SYD-AKL-LAX for about 20% cheaper than AKL-LAX direct.
One would assume the MEL-LHR via Dubai or Perth would be the same price or close to as you can fly other carriers about 60mins longer.
Prices will sink within a 6 month window of the date. I recently purchased Singapore A380 MEL-LHR $1100 4 months in advance. A year out it was $2500.
Last edited by PoppaJo; 27th Apr 2017 at 03:55.