With the North West Corner apron repaired after the removal of fencing and portocabins it has gone back into full use for parking biz jets.
I was looking at Signatures apron today that is next to Hangar 125, which is the Gulfstream hangar. It was created after an old hangar was knocked down maybe 2 or 3 years ago to replace lost parking on the Pond that has gone back to the airport for overnight parking.
Plenty of room there for a big hangar extension to Hangar 125 which could keep Gulfstream at Luton. It won't happen as Signature need the apron but if Gulfstream does move out of Luton it will be a significant event as it will be the first major consequence of airport expansion that has had such a negative impact on an existing business that they will be forced to move out of Luton.