for as long as i can remember some grey men in grey suits have been bickering on & on about a 3rd runway and in the meantime other cities have just got on with it & seem to have left London behind in terms of a modern efficient transport hub.
my own view is it's in the wrong place anyway, the road network around there can barely cope on a normal day nevermind when a minor incident occurs.
new runway at Gatwick & Manchester.
put more of the short hauls in & out at City.
divert most of the freight into Stansted, Luton, Brum, EastMidlands etc.
overall reducing the capacity at Heathrow gradually so it's a bit less crazy.
or just build Boris Island with 6 runways on the Thames :-)