It should be possible to build unmanned, remotely controlled submersible platforms containing one or more missile launchers. They could be placed on the ocean bed in suitable places anywhere in the world’s seas, and with a little ingenuity could be surreptitiously moved about a bit.
In a crisis they could be brought to the surface and remotely programmed and activated. There are other possible ways of building a deterrent.
It is no more necessary for sailors to risk their lives hundreds of feet under water for months than for coal miners nowadays to work for years in deep tunnels.
The hidden threat, so beloved by some of our politicians, only exits if it is impossible for sophisticated detection, with the know-how of the next few decades, to find a 20,000 ton sub.
I think any smart adversary could do this and, anyhow, I hate knowing that I belong to a state seen by many nations as a military bully.
If we don’t waste money on a new Trident programme we could afford properly equipped forces to deal with many smaller, and perhaps less militarily glamorous, threats to our security.