It was QF44 AKL-SYD, scheduled as 1800-1930. Person I knew on board said the reason they were given was staff shortages, but she wasn't able to say who was short of staff, QF, ATC, Customs, Ground staff?
Interestingly enough the QF website shows QF44 for yesterday as...
QF 44
Operated by: Qantas Airways
Depart:Auckland 31 Aug at 18:00
Arrive:Sydney 31 Aug at 21:50
Stopover:Brisbane for 0:30 hours
Total Time:5:50 hours
Aircraft:Boeing 767-300 - view seat map
Thanks