Industrial capacity matters when comparing defence budgets

A percentage of GDP is an incomplete measure of readiness. The historical interpretation offered here associates spending around three and a half to four percent with periods of successful deterrence, while warning that changing which costs are counted can inflate headline percentages. Earlier Britain possessed a much wider network of naval yards and military infrastructure, even after interwar consolidation, and maintained turnover sufficient to preserve skills and capacity. This does not imply that Britain was consistently ready for war; the comparison is that it retained infrastructure to recover from poor preparation. Major yards could close before both world wars while enough competing capacity remained to expand production. Readiness depended on what money had built and kept available over time.