Why identical J and K destroyers formed separate flotillas

Royal Navy ordering practice grouped identical ships into alphabetically named flotillas, so the J and K ships were built to the same theory but organized separately. The letter change therefore marked a second flotilla and ordering group, not a redesigned destroyer. Narvik shows the operational consequence: H-class ships entered the fighting together because ships sharing a class letter were grouped into the same flotilla. The later force that entered with HMS Warspite drew on several classes, which shows the difference between a standing flotilla and a task force assembled for a specific operation.