"Peel appear to have spent nearly £5 million pounds at the airport since their takeover and must be subsidising the running costs on a month to month basis."
maybe, but to a company with £4.5 Billion assets that's (very)small potatoes. The acquisition of 300 acres of land for 1/2 million quid, whether or not it has an airport on it, was a good deal, and with local authorities incapable of resisting any planning application for brownfield land use, it's a long term punt with inevitably a lucrative return in ten years time.
And don't dismiss the idea of Housing, Ingleby Barwick was once a farm, and was "never going to happen"