Not to mention the fact that the NATS En-Route side is bound by price capping set by the CAA in order to reduce the costs passed on to the airlines.
In short.... NATS bears the cost of the restructuring of airspace as a part-privatised industry left with mountains of debt by a Labour government under a financial regulation forced upon them by the CAA in order to reduce costs to the airlines that will inevitably benefit from the restructuring of the airspace by the increased no./more efficient operation of their flights.
Maybe it should all be paid for by the new tax that is being levied on passengers.... sounds only fair... bet it doesn't happen though!!