The National Planning Policy Framework (NPPF) is important to the protection of airfields in England. You can download a copy here. Does your local authority have a Local Plan that complies with the provisions for airfields and sports facilities? Does it specify that your airfield is not an area designated for development? If not you need to challenge it or there will be a presumption that a planning application to develop it will be automatically accepted. And then it will be too late.
Don't delay - look after your airfields!