Originally Posted by 500N
Why would you design your own and not go to the US and ask for one of theirs which is designed for ships, made, works and ready ?
Probably the cost of technology transfer, hardware, system integration, through-life support and updates, ongoing requirement for highly specific specialist training, skilled operation & maintenance, eventual decommissioning, etc. Not sovereign and could easily end up being even more expensive than a home-grown version.
Irrespective of the home-porting practicalities of a CVN's size (100 ktons vs 65 ktons) and nuclear nature, the UK could have gone the whole hog and ordered a couple of Gerald Fords with two reactors, EMALS and traps at around $13 bn each but HMG still wouldn't be able to afford them. Then there are a CVN's restrictions regarding use, berthing in foreign ports and training, sustaining and paying a crew four times as big to consider.