LHR certainly is in a completely unsuitable location but the time to have done something about it has long passed us by. How many other major airports have the main approach path straight over a capital city centre (or any city centre) subjecting all the residents to noise and exhaust pollution, let alone the potential for a terrorist act or other crash?

The 1970's and 80's would have been the time to build an alternative to the East of London (Maplin?) before the NIMBY and environmantal culture really took a grip LHR is virtually penned in by other developments on all 4 sides and cannot really expand much further past a third runway which I doubt will ever get built anyway.

Personally I think LGW and STN will be the airports that will be greatly expanded once LHR has T5 opened and the East terminal redevelopment completed. And if a high speed rail link connecting LGW-LHR-STN together is ever done it would solve alot of the connecting problems and allow the three airports to function in an integrated way. Don't hold your breath though.