Mr T, you have a talent it would seem. You are hereby anointed the musical bard of spotter's corner 2023-24.
So the 'Antonov' went by SW London at 11.26am and "wasn't an A380, different but bigger"...Might it have been a C17, or A400 or some freighter not on the normal trackers ? This person, whilst not a plane nut has enough daily sightings to recognise if something is different. I have no clue, but perhaps others might.