The first generation of new 1930s light cruisers

The class evolved from earlier Royal Navy cruiser work. Treaty limits and the focus on County-class heavy cruisers shaped the available design effort, while proven machinery and gun mounts gave the new light cruiser a practical foundation. The County programme had absorbed design talent partly because Britain could build few new capital ships under the treaties. The old system of holding many battleships and cruisers in reserve was no longer sustainable under treaty tonnage, tight post-war finances, and other government priorities, including the developing welfare state. Repeated imperial cruises would also wear out scarce battleships and battlecruisers far from major support infrastructure. The Leander was intended to provide a durable presence on distant stations without consuming those capital ships.