On a day of significance to the USA but not Australia, 4 July 2023, QF9, the mid afternoon 1505 hours MEL across to PER and then express to LHR is estimated to depart tonight at 2100, 355 minutes late, with suggested PER pushback becoming 0040 on Wednesday 5 instead of 1845 tonight, identically late. LHR arrival is likely to be after 1000 hours on Wednesday, so the 1155 hours ex London Heathrow QF10 may be delayed: too early to make an accurate prediction.
Noit sure why the delay as with a quick look there weren't any delays to arrivals such as QF22 from DFW and QF94 ex LAX, nor last night's QF10 ex PER and before that, LHR.