I think that most people accept (perhaps reluctantly), that we need to keep Trident and upgrade the submarines from the Vanguard class to the Dreadnought class.

Presumably because they believe that, in spite of the many objections to nuclear deterrents in principle, at least Trident is a deterrent; it helps to keep us safe.

However as far as I can see Trident is not an effective deterrent.

Back in 1968 when the first Polaris submarine was deployed it may have been undetectable, but in the more than 50 years since, technological advances have changed the situation.

For some years Russian submarines have not had to rely on sonar, but have been able to track others by sensing their wake, and Trident subs on patrol are moving.

Furthermore in future the use of swarms of drones is likely to replace manned vessels in tracking submarines. Assuming an enemy contemplated a nuclear 1st strike against Britain or its interests it would first destroy the Trident submarine on patrol and then launch the nuclear strike before Britain has time to deploy one of the other 3 Trident submarines.

It is worth noting that the National Security Strategy and Strategic Defence and Security Review 2015 does not examine the question of whether Trident is still an effective deterrent.

Annex A classifies Terrorism, Cyber attacks and Major Natural Hazards as Tier 1 threats as against nuclear war, Tier2.

In view of this why does the government insist on upgrading Trident without examining whether it is still a credible deterrent?

It gives the public a false sense of security and also allows us to remain in the nuclear club. But does this really enhance our reputation and influence in the world?