Trade protection was an insurance argument

Prewar maps made it appear easy to bar Italy or Japan from Britain's global sea lanes, but that calculation undervalued low-probability, high-cost disruption. Lost ships were only part of the damage: rerouting, delayed cargoes, economic opportunity costs, and diplomatic consequences also mattered. A modest tender force functioned like insurance by keeping patrol aviation and older surface units ready in distant theaters instead of demanding emergency diversions from the main fleet. The difficulty was political: an insurance argument only worked if decision-makers accepted spending on secondary theaters before a crisis made the need obvious.