Don't quite a lot of aeroplanes get 'lowish' over West London? In the jargon it's known at 'final approach', and comes just before 'landing'.
It is not a final approach flying over Esher
away from Heathrow.
It was so unusually low that SWMBO ( non airline person) phoned me to report that there was something amiss with an aircraft that had just passed over home.