Defence procurement is a complicated business. There is much governance, but this is trickle-down governance, with the most scrutiny being applied to the people at the bottom of the food chain, dealing with paltry amounts of money. The amount of time, energy and people's salaries being spent on governance is staggering. It can be ten times as difficult to spend £100 than £1M, it's just not scalable in the least.
When it comes to developing new products, there's too much tendency to try and please everyone, leading to acquiring products which are less effective in some ways than they should be, there's so much time and energy spent on trying to get the best overall product for the best deal that by the time the deal's done the world has moved on and the threat may have changed.
Because it's defence, its intensely political, there are political pressures to use certain providers as well as any technical and financial pressures. Sometimes procurements are proceeded with in spite of major faults with the capability or with the provider because of political pressures.
Overall though, I don't think we the public ask enough questions of our MPs and our government, we don't pester them enough to justify developing aircraft carriers, or tanks, or whatever really, and I don't know why that should be. Defence should be more transparent, but I guess then that the needs for defence, the current and possible future threats, should be more transparent also, we should have access to threat assessments, but there's this feeling in government and in defence that if the public knew about the threats we're facing, they'd be terrified. So again, another complication, are there genuine threats we need to protect ourselves against and if so, tell us what they are.
And, the UK has a tendency to get itself embroiled in conflicts which may not directly impact the UK. again this is hugely political, we the public should probably be questioning our government more, making them justify defence involvement.