Why a submarine deterrent must stay at sea

Why should a British strategic deterrent be submarine-based and continuously deployed?

A submarine at sea is survivable and avoids a provocative crisis deployment; maintaining that posture requires enough boats to keep one continuously available.

The answer argues that Britain's geography makes land-based missile silos politically and physically awkward. Suitable hardened sites are scarce, close to population and political centres, and likely to face local resistance. More importantly, trying to sail a deterrent submarine secretly during a crisis is itself escalatory. A credible British submarine deterrent therefore needs enough boats to keep one continuously at sea, or the country should choose not to maintain the capability at all.