Keeping strategic deterrence separate from tactical strike

Why not fire conventional cruise missiles from the same submarines that carry Britain's strategic nuclear deterrent?

Doing so would expose a deterrent submarine's location and create avoidable ambiguity between nuclear and conventional missions.

A ballistic-missile submarine is valuable because it remains hidden and survivable. Launching cruise missiles would reveal its area, add a routine conventional mission, and move it closer to tactical danger. The next attack-submarine class should instead include VLS capacity for conventional land-attack weapons, a capability omitted from the Astute class. Separate weapon systems also reduce the already small risk of confusing nuclear and conventional loads and make an adversary's interpretation of a launch clearer.