Apart from the Government still being under the illusion that they still own Heathrow & British Airways (probably fits on with many of their other current delusions). Why the hell should there be an overwhelming desire on their part to try to force every traveller and every ounce of freight through Heathrow?
I may just be a simple taxpayer (i.e one of the poor S.O.B.'s that has to pay for their largesse), but surely if the country had a more distributed availability of flights to the rest of the world, the south east corner of the country wouldn't be so overcrowded with overloaded & failing infrastructure. We probably wouldn't need to consider the same level of investment in road & rail just to try to bring more of the country into a reasonable travel time from Heathrow purely to justify the investment in Heathrow.
Being of a practical frame of mind, if the Government were truly serious about providing a world class facility with high safety standards, then they should give notice that Heathrow, Gatwick and Stansted would close within five years and their land given up for housing. These three airports should be replaced by a brand new airport out by Kelvedon / Tiptree or out in Norfolk/Suffolk where things are nice & flat and a proper multi-runway airport like Atlanta could be built with high speed dedicated rail links to various parts of the south of the country. Flight paths would be clear of major population centres at the higher risk landing / take off phases of flight and it could be built to suit today's & tomorrow's aircraft with extra -long runways to give longer take off and landing rolls which ould cut down noise by reducing thrust & reverse thrust needed. Five years notice might seem too short when you look at the saga of T5, but if Hong Kong could get a new airport on an island that didn't exist together with about 20 miles of multilane motorway and dual deck suspension bridges in the virtually the same period there's no reason why it can't happen on dry land here, other than lack of political will.