I'm struggling with Trident. Oh, it might be an expensive virility symbol that will ironically prove our impotence if we ever are attacked, but it is an unpredictable world out there and unilateral disarmament may not be the best policy in a rapidly proliferating world. I remember once trying to de-escalate an aggressive situation by sitting down, an act that resulting in my being kicked in the head!
(No, that doesn't explain any of my views!)
However, as this video shows, it does also provide an excellent example of the difference in the speed of light and of sound. Perhaps we could run school trips for Physics students to Faslane and conduct test firings so that they can calculate how far away the missile was when it was launched.