Uncertainty. Create uncertainty and all users will start looking over their shoulder. It is more than evident that GA does not form part of Biggin's future despite quiet protestations to the contrary.
I'm guessing that Biggin's future has been decided, it lies with that part of GA known by some, as Deep Pocket Bizjets Ltd. It is all about cash.
It might not be all that rosy on the development front. I seem to recall that in either the original or, subsequent versions of the Bromley Council lease there were restrictive covenants enshrining and promoting the continued active presence of General Aviation.
I again guess, that as public interest documents , copies of these leases and any amendments should be available from Bromley Councils archives.