Whilst not disagreeing in the slightest that this PFI is a crock of smelly stuff, I think if the MOD canned it at this stage the resulting litigation would keep my sort gainfully employed for many a year and cost the MOD a small fortune.
On top of that you'd then have to go out and fund the purchase of the aircraft, the in life support, the training, the specialist refeulling kit, the conversion, the spares support etc etc etc etc. All of which was supposed to be paid for through the 27 year life of the PFI.
Can't have it both ways.............................