Why Vanguard alone cannot cover a battleship threat

Vanguard is expected to beat Royal Sovereign in a direct encounter, but that does not guarantee her availability when needed. A single ship can cover only one location and becomes unavailable during refit. An opponent can exploit that interval instead of accepting the battle for which the ship was designed. The same criticism is applied to a navy with one aircraft carrier: a refit produces a period without its carrier capability. France's single-carrier arrangement is defended within the wider NATO pool of British, American, Italian and other carriers. Nuclear propulsion does not make a carrier undergoing major work immediately available for an emergency.