QF currently have scheduled 380 and 789 aircraft to LHR. Their only narrow body jets are 738s and 717s and, thankfully, they don’t go anywhere near LHR. The last time QF regularly scheduled narrow body aircraft to LHR was decades ago when 707s were operated.
I don't believe that that is true. istr Qantas used to run feeder services from Manchester to Heathrow using small aeroplanes