diginagain,
Portreath has a 'chemical (biological) germ warfare' or similar testing background which seems to be somewhat offputting to many people!
It's about the size of the field, Cornwall has no need for a mega expanse field and certainly no need for a 9,000ft runway such as St. Mawgan, the larger the field the more expensive the operating costs, just to illuminate a 9,000ft runway is 50% more expensive than it need be!
St. Mawgan will drain public funds this year, next year, the year after and for every year they continue to keep it open with public funding, Perranporth would be a 'one off' cost, Perranporth is already commercially viable (Portreath is not), give them a shiny new runway and taxiway or two, lighting, perhaps an ILS, a parking area and terminal, car park and then the council can wipe their hands of this annual financial burden whilst leaving Perranporth to get on with it.
As for road and transport (rail) connections, well the current Newquay airport doesn't have those anyway so any new airport has little, if anything, to improve upon in this respect.