Apologies if this has been mentioned. I've skim read the thread and don't think I've seen it...
The UK government has gone down the road of Trident because it is a credible 'second strike' system the whole point of which would only be used in the event of a nuclear attack on the UK or one of its allies that warrants a full scale nuclear response. An aggressor does not know where the return volley will come from therefore can never target it as part of the first strike. There in lies the deterrent. If the Nuclear deterrent lies with aircraft carriers, the whereabouts of which are easily found, then they can be targeted, which destroys the actual deterrent part. I guess what I'm saying is, that if we want a deterrent (and I think we definitely should have one!) then it has to be a second strike system to be effective and therefore has to be a boomer.