I don't know how they do it, but the MoD (customer) seems always to have a habit for making it very difficult for things to progress easily. Some recent examples (15 yrs) we've seen have been:
wanting a JTIDS type terminal on a jet. original price & spec too much, so a new bid with 'features-lite' option sent. agreed, then 1/2 way through implenentation & testing a request for "can we have all the functions please? - we've decided we now can't do without it" aaarg. time and costs wasted.
trying to get a 25mm guun on a jet. over 10 years of fiddling and mincing trying to sort it and failing.... no reason ever given why someone wouldn't own up, or just cancel it, or use the 30mm older one that was fine, or buy the US one of the shelf. probably some "i can't admit we're wrong" problems in the system somewhere
upgraded engines, more thrust, better hot weather perf, trialled in 1988 or so, got on the jet finally in 2005 ish. and the type that really needed it, it was OSD just as they were working on how to get the engine into it...!
and others, but you get the idea.......... Imagine how you'd feel if you tried to build a Ford Focus for someone who asked for FWD one week, then RWD the next, then changed the spec from a hatchback to an estate the next...! Or even how you'd feel if when you asked to buy a focus, Ford said 'Give us 10,000quid and a couple of years and we'll have a prototype', then 2 yrs later they wanted another 10k, and then 2 yrs after that, you paid another 10k, and got a car that only had 1 door, and would only drive 10 miles, and only in daylight......... unless you paid another 10k to fix it.....
CHF