PS. Sorry in the excitement of my "maths in public" I missed out on my opinion on your:
Also what happens when you want a bit of kit that’s not "off the shelf" then what are you going to do. Where are you going to go and how much do you think that nice foreign company is going to charge for it.
Probably less than BWoS!
Sorry, flippancy aside, I believe that the "home grown" and "operational sovereignty" arguments are long gone in the western-technology global-market. For example, say I want a new data-modem for my brand spanking MPA made by Britain's finest. The technology is available from BAES Inc in the US and is covered by ITAR and BAES in the UK apply for a TAA to build it. The technical ability to build more is still protected and only US nationals can do that - so if the UK wants more and the US say no, we're stuck. So we build a one-off and the costs soar as they have done with MRA4.
The B Word