I hope he won't mind me saying this, but given that Clive - no rookie at the time - comes across as eternally engaged and excited by the subject (not to mention sprightly in general) and is clearly keeping abreast of things, it would appear that working on projects of that ilk can confer a certain extended "youthful" outlook. Long may it continue!
The M3+ military projects were effectively rendered obsolete much faster by the advent of the space programme. I'm sure that the engineers to come that are worth their salt will be smart enough to engage with their predecessors and their work. I barely understood half of the stuff in this thread and I'm still hooked!