I've heard from more than one source that when Peel Investments (DTVA) Limited took over the airport from Peel Airports Limited, the south side was included in the deal and is now part of the airport again.
Of course that doesn't mean to say they will use said land for aviation-related development.
Before the sale I heard that Peel plc had been spooked by talk of an enquiry in parliament and that's why they gave the land back.