Bismark,
You say..... "There is a world of difference between what might be acceptable in UK/peacetime airspace, and what is required, on occasion, in a war-zone...." and you are of course correct.
However, what happens when the "ops only" clearance is applied to an aircraft flying "ops" in the UK in peacetime? Accepting a risk when troops are under fire is a relatively easy decision to take/justify. Accepting a similar risk in UK airspace when the results of not flying cannot be fully determined prior to launch is a different matter.
crab@SAAvn said "...surely an aircraft is either airworthy or not, it can't be both..." I'm not sure that his question has been answered by anyone subsequently. Unless people are saying that unairworthy aircraft are being flown on operations in times of extremis.
I assumed that aircraft were defined as being airworthy or not. Do we instead have a spectrum of airworthiness states, from fully airworthy to totally unairworthy with a range of in between definitions? If so, where, are they written down, and what guidance is there for the people who have to fly/authorise aircraft in an in-between airworthiness state?