Wader2
You are of course correct - not "excess" per se but irreducible spare capacity.
The point here is that the nature of both the military and the NHS is that it is essentially designed to carry excess capacity in peacetime to allow it to function properly in a crisis. The issue will always be what is the irreducible spare capacity that is required to ensure that what is needed to be delivered in a crisis, can be.
Treasury will always push for the irreducible spare capacity to be smaller (ie, cheaper) and MOD/NHS will always push for more capacity / capability (at higher cost): the political decision making is in where to strike that balance. Properly implemented SIWM helps bridge the gap, to provide more capability.
S41