yotty. things will get a hell of a sight worse on m25 if lhr gets it. you cannot rip up m25 ( up to 6 lanes each side in places) over a 2 to 3 mile stretch, realign it, widen it, tunnel it, lower it by 9 feet and build a runway/ taxiway/roads over it without massive disruption to the already overloaded motorway which will still have to find its way through/past the works for years during the reconstruction. and remember this is ripping up motorway only recently reconstructed prior to opening of T5.
london needs to develop a second major airport not just another runway to cope with the future and
lgw while not perfect is the best option. in a few years we will be saying why ever didnt we do this much earlier.