Imperial Britain did not devote roughly half of GDP to defence in this estimate. The maximum was nearer five or six percent, and spending was usually lower. Within that allocation, Britain favoured naval power because maintaining the Navy was cheaper than supporting the much larger army that an alternative grand strategy would require. The exchange distinguishes the scale of defence spending from the strategic choice of where the money went.
Notable Point · 1:29:25
Putting imperial defence spending in proportion
A correction places British imperial defence spending nearer five or six percent of GDP at its peak rather than anything approaching half of national output.