Not even sure that the Asbestos thing is a factor. As people have said, a cheap temporary (or even permanent) hangar is not that expensive and is an easy solution if that is all that is the issue.
I think the UAS had left before the original decision to close the airfield was overturned.
The sensible thing to do is of course, to move the UAS straight back in before it deteriorates but this requires a quick decision(which they won't do) and of course the facilities will deteriorate even further and then require a huge investment to bring up to scratch, and that will make it not cost effective so best leave them where they are at Boscombe and then sell off the airfield at Colerne (and we go full circle back to decision 1).
I actually think that having overturned the decision to close the airfield, MoD actually don't know what to do with it............................ they don't really have any flying units to put there permanently do they ?
Arc
I would suggest moving 621 VGS back in there maybe..................??