In this debate I guess I really have to qualify as a YIMBY (Yes, In My Back Yard) since I live within 10 kilometres of LHR and use it as a passenger on a weekly basis. Having such a major airport so close is undoubtedly beneficial to the logistics of my job, and my house is off the approach paths so all I get in the way of major noise at the moment are the Concordes currently going off 9L (and I still marvel when they do...).
I am also aware that of course LHR was originally designed (back in 1945/6) with six runways, plus a potential additional one north of the A4 as well as a two mile long canal for flying boats (what a shame that last one never got built - what a rowing lake it would make now!); no one could have been in any doubt, then or since, that it was set to be a very major airport.
However, few can dispute that LHR at present is an embarrassing disgrace. It has fallen way behind the standards of more recent new and upgraded international airports. Not only are its passenger facilities poorly provided, they are also abysmally maintained; I shudder each time I pass through, for instance, at the number of moving walkways that are out of service at any particular time; what must visitors think?!
I believe therefore that the time has come to make the very fundamental decision about LHR: either develop it properly into a 21st century airport, with all that that entails in terms of extra runways, terminals and infrastructure and demolition of homes and history, or close it down and build something decent somewhere else.
If it is to stay, then those of us who have chosen to live nearby, for whatever reason, have to accept the consequences of that choice, made as it was in the full knowledge of the implications of doing so ( After all, LHR was a much smokier, noisier place back in the 70s with all those 707s, DC8s and VC10s around). Let's though see some world-class infrastructure put in place there to make it work properly: an inter-terminal monorail, including a passenger pick-up/drop off point outside the congested central area, for instance, and a high-speed trainlink to LGW and STN would provide flexibility to run the three almost as a single "virtual" airport. There are now so many examples of airports that have been upgraded with proper investment to make them efficient and pleasant places to use (O'Hare, Newark and San Francisco (nearly!) come to mind...); we should be bold and copy their examples, or admit defeat at Heathrow, close it down and go elsewhere.