First time post here, please let me know if more detail needed (and which tag would suit it best).
I live in Essex UK, in the evening normally see lights of planes on approach to the London airports.
This evening (29 August 2019) from 21:00 BST / 20:00 UTC I have seen lights of planes flying away from London in large numbers (at least 30 when I started paying attention).
They were in groups of about 5, then another group following not far behind. They appeared to be heading in an easterly direction away from London.
Could someone help to shed some light on this? Have lived in this area for 15 years and never seen anything like this.