New Delhi, July 21 -- a man who spent four years rebuilding Britain's depleted armed forces had just been handed control of the national economy.

John Healey, 67, who served as Defence Secretary under Keir Starmer and was widely credited with pushing Britain's formal defence spending commitment toward three percent of gross domestic product, brings credentials to the Treasury that no recent chancellor has carried. Most incumbents arrived from the financial sector, academia, or the career civil service. Healey arrives knowing what a combat-ready frigate costs, how long the procurement pipeline runs, and what it means to fight a spending battle against a sceptical Treasury from the wrong side of the table.

Burnham said at Downing Street t...