Sorry RJ, I fail to see the national benefit in this.
All I see is peoples homes being demolished, additional traffic on the M25 car park and access roads to LHR, even longer queues at check-in and subsequent security, more (over) crowding in the terminals, longer waits for baggage collection, more flights over London etc etc etc.
It might suit you southern softies folks, but people from north of the M25 would have been better suited by expansion of regional airports to allow some of the holiday type traffic to leave LHR, freeing it up for the so-called business traveller. For our business travel, LHR ADDS 2 hours or more and all I see are the commuter type flights leaving regional and heading to LHR
It's about time people realised the UK is more, much more, than London and the SE