A bit of a controversial view but exactly what is the problem with noise at LHR.
I grew up very close to Heathrow and in the 60s and 70s noise was an issue. , VC10s and other Conway engined beasts would have woken all of west London on a night easterly departure and the ear splitting scream of JT3s on approach the same.
But life is very very different now , the airport has been there for 70 plus years so no one has suddenly found out that there is an airport near their house. I dont know what the decibel numbers say but the likes of 787s , 350s and Airbus 320s dont make anything like the noise so an extension of operating hours would seem sensible.
Of course that would upset the citizens of Richmond but as there seems to be no other alternative why not give it a try