For most of the twentieth century Britain possessed both the world’s largest merchant fleet and its most extensive overseas territories. It is not surprising, therefore, that the Royal Navy always showed a particular interest in the cruiser a multi-purpose warship needed in large numbers to defend trade routes and police the empire. Above all other types, the cruisers competing demands of quality and quantity placed a heavy burden on designers, and for most of the inter-war years Britain sought to square this circle through international treaties restricting both size and numbers. In the process she virtually invented the heavy cruiser and inspired the large 6in-armed cruiser, neither of which, ironically, served her best interests. This book seeks to comprehend the full policy background, from which a different and entirely original picture emerges of British cruiser development.