There is even an interesting article on this:
https://www.euroga.org/forums/hangar...by-se-aircraft
I had considered the glide clear rule but as I'm heading diagonally away from LCY (if that makes sense) ie. routing towards Dartford I believe I maintain glide clear (Thames...) - I will do some more calculations.
NB. I'd be flying at 2400ft (as far as I can go without getting into the LTMA), I guess LCY counts as a 'good' place to land (given it's a runway...)