They have become so increasingly unfriendly to GA, I am not sure it makes much difference. I would hazard a guess it is to extend the size of the apron, and may be create a new taxiway at the South end. they have probably got one of their periodic delusions of grandeur re growth in charter/scheduled traffic.
Cancel that nonsense. I have just phoned them, and that delightful girl who works in the office (the best bit about the place IMHO) says it is to allow the runway to be reinforced.
Skua