its asking people to honour their promises and estimates, and to stop using the Exchequer as if its a bottomless pit of cash for the RAF
GrahamO, that's probably how the Treasury looks at things and - as such - I think your point is important. However, I disagree with your basic assessment.
The first financial black hole is procurement, and in my experience the basic reason for that is politics a long way outside of the control of the MoD. Essentially, the insistence of the government of the day to buy British - such that no major projects ever go to true competitive tender - means that cost overruns are inevitable; there is just no incentive for cutting costs. That's not in any way a criticism of the defence industry, who exist to make money for their shareholders as best they can. Neither am I suggesting that it isn't occasionally appropriate to subsidise the UK defence industry... But the current Defence Industrial Strategy is an expensive fudge.
The second problem is that governments set out planning assumptions for what they ask the Services to do, and then ask the MoD to do something else entirely. The Services are flexible and can do that... But it costs. There are two basic approaches to funding public services: you can decide something is desireable, work out what the country can afford, and fund the service as best you can. Or you can decide something is essential and fund what it costs. But you can't have it both ways: deploying forces because it's apparently essential and funding them as if it's apparently desireable is always going to end in a budget and/or capability train wreck.