I would commend the General Aviation Awareness Council/DfT survey, which is aimed at establishing the actual and quantifyable benefit of GA airfields to (chosing these words with care) the communities they serve.
This survey is still very much under way. I had the pleasure of first distrubuting the 'Pilot & Aerodrome Questionnaire' in AOPA's General Aviation magazine - we had a superb 15% take-up (ask any publisher what kind of response they get, even to a reader offer, to put this in context).
I really think that the best way to protect airfields is through making a cast-iron case for their usefulness to officialdom.