Anyway, the trip back. The flight was NZ38 on Air New Zealand, Heathrow [EGLL], Hong Kong [VHHH] (for a brief stop) then on to Auckland [NZAA]. I then caught a domestic AirNZ flight from Auckland to Wellington [NZWN]. The international portion was on a Boeing 777-219ER, ZK-OKA, as per the first photo from Heathrow.
Unlike the trip over, standby upgrades were not available, although this was no problem as I had one of the best economy class seats on the aircraft, with no seat directly in front of me. Perhaps some of the exit row seats were marginally better, but I'm very happy with what I had. As usual, the food was good, the flight attendants very good, and apart form the lack of sleep [I never seem to sleep well on aircraft], a good way to get from A to B.