Do you really think you can get planning permission for the world's biggest airport around Huntingdon? Good luck to you if you eant to try. It is political suicide; the land costs would be stratospheric; the high powered opposition would be insurmountable; there would be endangered species discovered everywhere.......
When RAF Alconbury was first being mooted as a likely new regional airport (though i beleave the plan at the time was a new luton rather than a new heathrow) it actually received WIDE local approval. Most people in Huntingdon/St Neots and surroundings seemed to support the plan. Along with that the land purchace woulnt hae been an issue as the government already owned most of the land needed, though they dont anymore as the site has now/is now being developed into a private business park.