There are underused runways already at Sothend and Manston.
Indeed.And with Heathrow bursting at the seams, the fact that those runways remain underused should speak volumes.....
The reality is that what we need is one world class purpose built airport, conveniently close to London yet sufficiently far away that the layout can be planned for maximum efficiency and minimum stress rather than dictated by site constraints. 4 runways, with room for at least one more, and 2-3 terminals with room for more if needed, but designed with ease of transfer in mind.
Personally I'm with those who say we should expand an existing airport rather than start over. And while Taildragger was a bit cryptic, if he was hinting at Stansted then I would agree. Unfortunately it would take a huge amount of political balls to bite the bullet and wind Heathrow down, and the infrastructure investment needed would be immense. But the alternative would be to stick with an increasingly unpleasant and congested alternative.