Are you trying to say that trident is an investment that we see a return on? What's that then?
That would depend upon (a) how you define 'return. (b) whether our seat on the UNSC is inextricably linked to our status and (c) How does our position as a Nuclear Power determine our standing in such international and treaty arrangements such as NATO? (d) Does our possessing a Nuclear Deterrent contribute to innovation and technology as it once did?