Your belief is that it is seen by HMG as retaining influence and therefore a seat on the P5. I probably agree with you that they see it that way, but I think they're wrong!
Concur. I think it is a bit of a hangover from when the nuclear club was more exclusive and an independant UK deterrent bought us influence with the US. I suspect the main driver is that HMG wish to retain approximate military parity with France. Some may argue that this is also a factor with CVF.
Anyway, I'm off for a pint before the storm arrives!!!
Regards,
MM