You have only to listen to any broadcast from Central London to realise why Heathrow should close,apart from all the congestion and lack of space for expansion. Why not "Boris Island" Aligned 23/05 with at least 6 runways with transport links north and South along a barrier across the estuary opening up East Kent and Essex and generating tidal power for the airport? Think big!
Of course,any political party that starts it will have it immediately cancelled by the next government,like most of our potentially great aviation achievements.
Heathrow has been a millstone round the neck of commercial aviation,in Britain,for decades.It's about time we bit the bullet.